Asp.net controls are not accessible in code behind

I have a project that was previously built by someone else. When I try to add a new control to the page, I can't access it in the code behind. When I try to access it there's an error message that the Control is not defined in the current context.

<%@ Page Language="C#" MasterPageFile="~/HRMS.Master" AutoEventWireup="true" CodeBehind="manageEmployee.aspx.cs" Inherits="HRMS.manageEmployee" Title="Untitled Page" %>

<%@ Register Assembly="eWorld.UI" Namespace="eWorld.UI" TagPrefix="ew" %>
<%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="cc1" %>


<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<script type="text/javascript">
document.getElementById("employee").setAttribute("class", "selected");
</script>
<!--OPEN CONTENT DIV-->

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<!-- Only this area is updated on PostBack -->

<div class="manage_employ">

<ul>
<li style="margin-top:10px; margin-bottom:15px"><input type="image" src="images/img_manageEmployee01.png"/></li>
</ul>

<ul>
<li>First name</li>
<li><asp:TextBox runat="server" class="text_input" id="txtFirstName"/></li>
<asp:RequiredFieldValidator ID="validatorFirstName" runat="server" ErrorMessage="*" ControlToValidate="txtFirstName"></asp:RequiredFieldValidator>
<li>Last name</li>
<li><asp:TextBox runat="server" class="text_input" id="txtLastName"/></li>
<asp:RequiredFieldValidator ID="validatorLastname" runat="server" ErrorMessage="*" ControlToValidate="txtLastName"></asp:RequiredFieldValidator>
</ul>

<ul>
<li>CNIC</li>
<li><asp:TextBox runat="server" class="text_input" id="txtCNIC"/></li>
<asp:RequiredFieldValidator ID="validatorCNIC" runat="server" ErrorMessage="*" ControlToValidate="txtCNIC"></asp:RequiredFieldValidator>
<li>Blood Group</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlBloodGroup">
<asp:ListItem>A+</asp:ListItem>
<asp:ListItem>B+</asp:ListItem>
<asp:ListItem>AB+</asp:ListItem>
<asp:ListItem>A-</asp:ListItem>
<asp:ListItem>B-</asp:ListItem>
<asp:ListItem>AB-</asp:ListItem>
<asp:ListItem>O+</asp:ListItem>
<asp:ListItem>O-</asp:ListItem>
</asp:DropDownList>
</li>
</ul>

<ul>
<li>Mobile</li>
<li><asp:TextBox runat="server" class="text_input" id="txtMobile"/></li>
<asp:RequiredFieldValidator ID="validatorMobile" runat="server" ErrorMessage="*" ControlToValidate="txtMobile"></asp:RequiredFieldValidator>
<li>Phone</li>
<li><asp:TextBox runat="server" class="text_input" id="txtPhone"/></li>
</ul>

<ul>


</ul>

<ul>
<li>E-Mail</li>
<li><asp:TextBox runat="server" class="text_input" id="txtEmail"/></li>
<asp:RegularExpressionValidator ID="valEmail" ControlToValidate="txtEmail" runat="server" ErrorMessage="*" ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*">*</asp:RegularExpressionValidator>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<li>Maritial Status</li>
<li>
<asp:RadioButton ID="rbtnMarried" AutoPostBack="true" runat="server" oncheckedchanged="rbtnMarried_CheckedChanged"/>Married
<asp:RadioButton ID="rbtnUnmarried" AutoPostBack="true" runat="server"
oncheckedchanged="rbtnUnmarried_CheckedChanged"/>Unmarried
</li>
</ContentTemplate>
</asp:UpdatePanel>
</ul>

<ul>
<li>Permanant Address</li>
<li><asp:TextBox runat="server" class="text_input" id="txtPermanantAddress"/></li>
<asp:RequiredFieldValidator ID="validatorPAddress" runat="server" ErrorMessage="*" ControlToValidate="txtPermanantAddress"></asp:RequiredFieldValidator>
<li>Temporary Address</li>
<li><asp:TextBox runat="server" class="text_input" id="txtTemporaryAddress"/></li>
<asp:RequiredFieldValidator ID="validatorTAddress" runat="server" ErrorMessage="*" ControlToValidate="txtTemporaryAddress"></asp:RequiredFieldValidator>
</ul>


<ul>
<li>Salary</li>
<li><asp:TextBox runat="server" class="text_input" id="txtSalary"/></li>
<asp:RequiredFieldValidator ID="validatorSalary" runat="server" ErrorMessage="*" ControlToValidate="txtSalary"></asp:RequiredFieldValidator>
<li>Joining Date</li>

<li>
<%--<ew:calendarpopup ID="calJoiningDate" runat="server"></ew:calendarpopup>--%>
<asp:TextBox ID="CalJoiningDate1" runat="server" CssClass="text_input"></asp:TextBox>
<cc1:CalendarExtender ID="CalJoiningDate1_CalendarExtender" runat="server"
Enabled="True" TargetControlID="CalJoiningDate1">
</cc1:CalendarExtender>
</li>


</ul>
<ul>
<li>Job Area</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlJobArea"/></li>
<li>Desigantion</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlDesignation"/></li>
</ul>

<asp:UpdatePanel ID="updatePnl" runat="server">
<ContentTemplate>
<div>
<ul>
<li style="margin-top:20px; margin-bottom:15px"><input type="image" src="images/img_jobHistory.png" /></li>
</ul>

<ul>
<li>Company</li>
<%--<asp:DropDownList runat="server" class="text_input" id="ddlCompany"
onselectedindexchanged="ddlCompany_SelectedIndexChanged"/>--%>
<li><asp:TextBox ID="CompanyNames" runat="server" CssClass="text_input"></asp:TextBox>
<cc1:AutoCompleteExtender ID="CompanyNames_AutoCompleteExtender" runat="server"
DelimiterCharacters="" Enabled="True" ServicePath="getCompanies.asmx" ServiceMethod="getCompaniesMethod" MinimumPrefixLength="1"
TargetControlID="CompanyNames" UseContextKey="True">
</cc1:AutoCompleteExtender>
<li>Job Duration</li>
<li>
<asp:TextBox ID="txtJobDuration" runat="server" class="text_input" />
</li>
<asp:RequiredFieldValidator ID="validatorJobDuration" runat="server"
ControlToValidate="txtJobDuration" ErrorMessage="*"
ValidationGroup="jobHistory"></asp:RequiredFieldValidator>
</li>
</ul>

<ul>
<li>Job Area</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlJobHistJobArea"/></li>
<li>Designation</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlJobHistoryDesignation"/></li>
</ul>

<ul>
<li>Last Drawn Salary</li>
<li><asp:TextBox runat="server" class="text_input" id="txtLastDrawnSalary"/>
</li>
<asp:RequiredFieldValidator ID="validatorLastDrawnSalary" runat="server" ValidationGroup="jobHistory" ErrorMessage="*" ControlToValidate="txtLastDrawnSalary"></asp:RequiredFieldValidator>
</ul>

<ul>
<li style="margin-left:160px">
<asp:ImageButton src="images/btn_Add.png" runat="server" ID="btnAddJobHistory" onclick="btnAddJobHistory_Click" CausesValidation="True" ValidationGroup="jobHistory"/>
<asp:ImageButton src="images/btnReset.png" runat="server" ID="btnResetJH" CausesValidation="False" onclick="btnResetJH_Click"/>
</li>
</ul>

<ul style="margin-left:30px">
<asp:GridView ID="grdJobHistory" runat="server" AutoGenerateColumns="False" Width="798px"
AllowPaging="True"
onpageindexchanging="grdJobHistory_PageIndexChanging"
onrowcommand="grdJobHistory_RowCommand"
onrowdeleting="grdJobHistory_RowDeleting"
onrowediting="grdJobHistory_RowEditing" Font-Bold="True"
Font-Names="Calibri" Font-Size="Medium" ForeColor="White" PageSize="5">
<Columns>
<asp:BoundField DataField="EmployeeExperianceId"
HeaderText="EmployeeExperianceId" />
<asp:BoundField HeaderText="Company" DataField="CompanyName" ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField DataField="JobAreaName" HeaderText="Job Area" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Smaller" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Designation" DataField="DesignationName"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Experiance Duration" DataField="ExperianceDuration"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Salary" DataField="LastDrawnSalary" ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:TemplateField AccessibleHeaderText="Edit" HeaderText="Edit">
<ItemTemplate>
<asp:ImageButton ID="imgBtnEdit" runat="server" ImageUrl="images/updateIcon.png" CausesValidation="False" CommandName="Edit" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeExperianceId") %>'/>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField AccessibleHeaderText="Delete" HeaderText="Delete">
<ItemTemplate>
<asp:ImageButton ID="imgBtnDelete" runat="server" ImageUrl="images/deleteIcon.png" CausesValidation="False" CommandName="Delete" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeExperianceId") %>' OnClientClick="return confirm('Are you sure you want to delete this record...');"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<HeaderStyle BackColor="#5D92B9" BorderStyle="None" />
<AlternatingRowStyle BackColor="#AAAAAA" />
</asp:GridView>
</ul>

</div>

<div>
<ul>
<li style="margin-top:20px; margin-bottom:15px"><input type="image" src="images/img_skillDetail.png" /></li>
</ul>

<ul>
<li>Skill</li>
<!--<li><asp:DropDownList runat="server" class="text_input" id="ddlSkill"/></li>-->
<li>
<asp:TextBox ID="SkillAutoComplete" runat="server" CssClass="text_input"></asp:TextBox>
<cc1:AutoCompleteExtender ID="SkillAutoComplete_AutoCompleteExtender"
runat="server" DelimiterCharacters="" Enabled="True" ServicePath="getSkills.asmx" ServiceMethod="getAllSkills" MinimumPrefixLength="1"
TargetControlID="SkillAutoComplete">
</cc1:AutoCompleteExtender>
</li>
<li>Skill Detail</li>
<li><asp:TextBox runat="server" class="text_input" id="txtSkillDetail"/></li>
<asp:RequiredFieldValidator ID="validatorSkillDetail" runat="server" ValidationGroup="skill" ErrorMessage="*" ControlToValidate="txtSkillDetail"></asp:RequiredFieldValidator>
</ul>

<ul>
<li style="margin-left:160px">
<asp:ImageButton src="images/btn_Add.png" runat="server" ID="btnAddSkill" CausesValidation="True" ValidationGroup="skill" onclick="btnAddSkill_Click"/>
<asp:ImageButton src="images/btnReset.png" runat="server" ID="btnResetSkill" CausesValidation="False" onclick="btnResetSkill_Click"/>
</li>
</ul>

<ul style="margin-left:30px">
<asp:GridView ID="grdSkill" runat="server" AutoGenerateColumns="False" Width="798px"
AllowPaging="True"
onpageindexchanging="grdSkill_PageIndexChanging"
onrowcommand="grdSkill_RowCommand"
onrowdeleting="grdSkill_RowDeleting"
onrowediting="grdSkill_RowEditing" Font-Bold="True"
Font-Names="Calibri" Font-Size="Medium" ForeColor="White" PageSize="5">
<Columns>
<asp:BoundField HeaderText="EmployeeSkillId" DataField="EmployeeSkillId" >
</asp:BoundField>
<asp:BoundField DataField="SkillName" HeaderText="Skill Name" ReadOnly="True">
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Skill Detail" DataField="SkillDetail"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="imgBtnEdit" runat="server" ImageUrl="images/updateIcon.png" CausesValidation="false" CommandName="Edit" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeSkillId") %>'/>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="imgBtnDelete" runat="server" ImageUrl="images/deleteIcon.png" CommandName="Delete" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeSkillId") %>' OnClientClick="return confirm('Are you sure you want to delete this record...');"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<HeaderStyle BackColor="#5D92B9" BorderStyle="None" />
<AlternatingRowStyle BackColor="#AAAAAA" />
</asp:GridView>
</ul>
</div>

<div>
<ul>
<li style="margin-top:20px; margin-left:20px; margin-bottom:15px"><input type="image" src="images/img_qualificationDetail.png" /></li>
</ul>

<ul>
<li>Course</li>
<li><asp:DropDownList runat="server" class="text_input" id="ddlCourse"/></li>
<li>Institution</li>
<li><asp:TextBox runat="server" class="text_input" id="txtInstitution"/></li>
<asp:RequiredFieldValidator ID="validatorInsitution" runat="server" ValidationGroup="course" ErrorMessage="*" ControlToValidate="txtInstitution"></asp:RequiredFieldValidator>
</ul>

<ul>
<li>Duration</li>
<li><asp:TextBox runat="server" class="text_input" id="txtCourseDuration"/></li>
<asp:RequiredFieldValidator ID="validatorDuration" runat="server" ValidationGroup="course" ErrorMessage="*" ControlToValidate="txtCourseDuration"></asp:RequiredFieldValidator>
<li>Passing Year</li>
<li>
<asp:TextBox ID="calPassingYear1" runat="server" CssClass="text_input"></asp:TextBox>

</li>
<!--<li><ew:CalendarPopup ID="calPassingYear" runat="server"></ew:CalendarPopup></li>-->
</ul>

<ul>
<li>Marks/Percentage/GPA</li>
<li><asp:TextBox runat="server" class="text_input" id="txtMarksPercentage"/></li>
<asp:RequiredFieldValidator ID="validatorMarks" runat="server" ValidationGroup="course" ErrorMessage="*" ControlToValidate="txtMarksPercentage"></asp:RequiredFieldValidator>
<li style="margin-left:160px">
<asp:ImageButton src="images/btn_Add.png" runat="server" ID="btnAddCourse" CausesValidation="True" onclick="btnAddCourse_Click" ValidationGroup="course"/>
<asp:ImageButton src="images/btnReset.png" runat="server" ID="btnResetCourse" CausesValidation="False" onclick="btnResetCourse_Click" />
</li>
</ul>

<ul style="margin-left:30px">
<asp:GridView ID="grdCourse" runat="server" AutoGenerateColumns="False" Width="798px"
AllowPaging="True"
onpageindexchanging="grdCourse_PageIndexChanging"
onrowcommand="grdCourse_RowCommand"
onrowdeleting="grdCourse_RowDeleting"
onrowediting="grdCourse_RowEditing" Font-Bold="True"
Font-Names="Calibri" Font-Size="Medium" ForeColor="White" PageSize="5">
<Columns>
<asp:BoundField DataField="EmployeeQualificationId"
HeaderText="EmployeeQualificationId" />
<asp:BoundField HeaderText="Course" DataField="CourseTitle" ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Institution" DataField="InstitutionName"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Duration" DataField="Duration"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Passing Year" DataField="YearOfPassing"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:BoundField HeaderText="Marks/Percentage/GPA" DataField="MarksPercentage"
ReadOnly="True" >
<ItemStyle Font-Names="Calibri,Verdana,Arial,Helvetica,sans-serif"
Font-Size="Small" ForeColor="#3F4A53" />
</asp:BoundField>
<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="imgBtnEdit" runat="server" ImageUrl="images/updateIcon.png" CausesValidation="false" CommandName="Edit" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeQualificationId") %>'/>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="imgBtnDelete" runat="server" ImageUrl="images/deleteIcon.png" CommandName="Delete" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "EmployeeQualificationId") %>' OnClientClick="return confirm('Are you sure you want to delete this record...');"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<HeaderStyle BackColor="#5D92B9" BorderStyle="None" />
<AlternatingRowStyle BackColor="#AAAAAA" />
</asp:GridView>
</ul>
</div>
</ContentTemplate>
</asp:UpdatePanel>
<ul>
<li style="margin-left:90px; margin-bottom:10px;">
<asp:ImageButton ID="btnSubmit" AlternateText="submit button" runat="server" src="images/btn_Submit.png" onclick="btnSubmit_Click"/>
</li>
</ul>
</div>
<!--CLOSE CONTENT DIV-->

</asp:Content>

For Example:

When I was trying to add some ASP.NET server side controls like `<asp:testBox id="txtBox" runat="server"/>` they were not accessible in the code behind.:

> Error: txtBox is not defined in the current Context ...

What am I doing wrong?

First

- Make sure you assigned an ID to the
control

If this doesn't help

- Close the page where you added the
control
- Rebuild/compile the project
and open the page again

manually enter declaration in other partial class

Make sure the codeBehind attribute in page directive refer to the cs file where you call the control

if you are unable to find the control in .cs page, simply add the control reference in designer.cs page and try to access it again.

I'm sure it will 100%. this is what i learned

Check to ensure the designer.cs file for the page is included in the project. Right click it and see if you get the option to "Include in project."

This happens especially with older stuff in visual studio.

In 1.1 (before "partial classes") you could always see the control declarations in the code-behind.

In later versions, they moved that into a cs.designer file (so now you've got partial classes -- part in the .cs.designer file, and part in the .cs file).

If you're working with a visual studio "project", then you can open the cs.designer file, and add your control. Just look at how all of the other controls are declared -- that's all you have to do.

If you're working with a visual studio "website", then you're out of luck. There's no way to view or edit the cs.designer file, because it isn't there until the website is compiled.

I had this problem when I moved a website into a main solution by creating an asp.net application project in the solution and copying aspx & aspx.cs files over. I solved it by right clicking on the project and converting to a web application. This created the necessary designer.cs files which contain the code for the asp objects on the aspx page.

Just found this question, and I realise it's quite old, but I think I have a potential answer. Your code-behind for the designer's partial class might not be included in the project - sometimes happens when you've renamed and/or copied the file.

Go to your page (let's call it Test.aspx) and expand its tree in the Solution Explorer - do you see a file called Test.aspx.cs *and* Test.aspx.designer.cs? If not, look for a button at the top of the Solution Explorer marked Show All Files. Click it - if you now see the .designer.cs file there, right-click it and select "include in project". This got me going again after I ran into this problem.

Have you renamed your project file? If you have, then remember to rename the Inherits at the top of your ASPX page.