I'm sorry i couldn't replicate the issue,the references are same as that in the example.
to add a checkbox,you can directly drag and drop a checkbox into the form template,where you want it.
For further reference,I'm attaching my full code where i tried. You can use the same code behind from the demo.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="EditFormTemplate.aspx.cs"
Inherits="Radgrid2_EditFormTemplate" %>
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<
head
runat
=
"server"
>
<
title
></
title
>
</
head
>
<
body
>
<
form
id
=
"form1"
runat
=
"server"
>
<
div
>
<
asp:Label
ID
=
"Label1"
runat
=
"server"
EnableViewState
=
"False"
Font-Bold
=
"True"
ForeColor
=
"#FF8080"
>
</
asp:Label
>
<
asp:Label
ID
=
"Label2"
runat
=
"server"
EnableViewState
=
"False"
Font-Bold
=
"True"
ForeColor
=
"#00C000"
>
</
asp:Label
>
<
asp:ScriptManager
ID
=
"ScriptManager1"
runat
=
"server"
>
</
asp:ScriptManager
>
<
telerik:RadGrid
ID
=
"RadGrid1"
runat
=
"server"
CssClass
=
"RadGrid"
GridLines
=
"None"
AllowPaging
=
"True"
PageSize
=
"20"
AllowSorting
=
"True"
AutoGenerateColumns
=
"False"
ShowStatusBar
=
"true"
AllowAutomaticDeletes
=
"True"
AllowAutomaticInserts
=
"True"
AllowAutomaticUpdates
=
"True"
DataSourceID
=
"SqlDataSource1"
OnItemDeleted
=
"RadGrid1_ItemDeleted"
OnItemInserted
=
"RadGrid1_ItemInserted"
OnItemUpdated
=
"RadGrid1_ItemUpdated"
OnItemCommand
=
"RadGrid1_ItemCommand"
OnPreRender
=
"RadGrid1_PreRender"
>
<
MasterTableView
CommandItemDisplay
=
"TopAndBottom"
DataSourceID
=
"SqlDataSource1"
DataKeyNames
=
"EmployeeID"
>
<
Columns
>
<
telerik:GridEditCommandColumn
>
</
telerik:GridEditCommandColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"EmployeeID"
HeaderText
=
"ID"
DataField
=
"EmployeeID"
>
<
HeaderStyle
ForeColor
=
"Silver"
Width
=
"20px"
></
HeaderStyle
>
<
ItemStyle
ForeColor
=
"Gray"
></
ItemStyle
>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"TitleOfCourtesy"
HeaderText
=
"TOC"
DataField
=
"TitleOfCourtesy"
>
<
HeaderStyle
Width
=
"60px"
></
HeaderStyle
>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"FirstName"
HeaderText
=
"FirstName"
DataField
=
"FirstName"
>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"LastName"
HeaderText
=
"LastName"
DataField
=
"LastName"
>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"HireDate"
HeaderText
=
"Hire Date"
DataField
=
"HireDate"
DataFormatString
=
"{0:d}"
>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
UniqueName
=
"Title"
HeaderText
=
"Title"
DataField
=
"Title"
>
</
telerik:GridBoundColumn
>
<
telerik:GridButtonColumn
CommandName
=
"Delete"
Text
=
"Delete"
UniqueName
=
"column"
>
</
telerik:GridButtonColumn
>
</
Columns
>
<
EditFormSettings
EditFormType
=
"Template"
>
<
FormTemplate
>
<
table
id
=
"Table2"
cellspacing
=
"2"
cellpadding
=
"1"
width
=
"100%"
border
=
"0"
rules
=
"none"
style
=
"border-collapse: collapse;"
>
<
tr
class
=
"EditFormHeader"
>
<
td
colspan
=
"2"
style
=
"font-size: small"
>
<
b
>Employee Details</
b
>
</
td
>
</
tr
>
<
tr
>
<
td
colspan
=
"2"
>
<
b
>Company Info:</
b
>
</
td
>
</
tr
>
<
tr
>
<
td
>
<
table
id
=
"Table3"
cellspacing
=
"1"
cellpadding
=
"1"
width
=
"250"
border
=
"0"
class
=
"module"
>
<
tr
>
<
td
>
</
td
>
<
td
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Country:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox7"
runat
=
"server"
Text='<%# Bind("Country") %>'>
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
City:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox8"
runat
=
"server"
Text='<%# Bind("City") %>' TabIndex="1">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Region:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox9"
runat
=
"server"
Text='<%# Bind("Region") %>' TabIndex="2">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Home Phone:
</
td
>
<
td
>
<
telerik:RadMaskedTextBox
ID
=
"HomePhoneBox"
runat
=
"server"
SelectionOnFocus
=
"SelectAll"
Text='<%# Bind("HomePhone") %>' PromptChar="_" Width="300px" Mask="(###) ###-####"
TabIndex="3">
</
telerik:RadMaskedTextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Birth Date:
</
td
>
<
td
>
<
telerik:RadDatePicker
ID
=
"BirthDatePicker"
runat
=
"server"
MinDate
=
"1/1/1900"
DbSelectedDate='<%# Bind("BirthDate") %>'
TabIndex="4">
</
telerik:RadDatePicker
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Title Of Courtesy
</
td
>
<
td
>
<
asp:DropDownList
ID
=
"ddlTOC"
runat
=
"server"
SelectedValue='<%# Bind("TitleOfCourtesy") %>'
DataSource='<%# (new string[] { "Dr.", "Mr.", "Mrs.", "Ms." }) %>' TabIndex="7"
AppendDataBoundItems="True">
<
asp:ListItem
Selected
=
"True"
Text
=
"Select"
Value
=
""
>
</
asp:ListItem
>
</
asp:DropDownList
>
</
td
>
</
tr
>
</
table
>
</
td
>
<
td
>
<
table
id
=
"Table1"
cellspacing
=
"1"
cellpadding
=
"1"
width
=
"250"
border
=
"0"
class
=
"module"
>
<
tr
>
<
td
>
Notes:
</
td
>
</
tr
>
<
tr
>
<
td
>
<
asp:TextBox
ID
=
"TextBox1"
Text='<%# Bind("Notes") %>' runat="server" TextMode="MultiLine"
Rows="5" Columns="40" TabIndex="5">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Address:
</
td
>
</
tr
>
<
tr
>
<
td
>
<
asp:TextBox
ID
=
"TextBox6"
Text='<%# Bind("Address") %>' runat="server" TextMode="MultiLine"
Rows="2" Columns="40" TabIndex="6">
</
asp:TextBox
>
</
td
>
</
tr
>
</
table
>
</
td
>
</
tr
>
<
tr
>
<
td
colspan
=
"2"
>
<
b
>Personal Info:</
b
>
</
td
>
</
tr
>
<
tr
>
<
td
>
<
table
id
=
"Table4"
cellspacing
=
"1"
cellpadding
=
"1"
width
=
"250"
border
=
"0"
class
=
"module"
>
<
tr
>
<
td
>
FirstName:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox2"
Text='<%# Bind( "FirstName") %>' runat="server" TabIndex="8">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Last Name:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox3"
Text='<%# Bind( "LastName") %>' runat="server" TabIndex="9">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Hire Date:
</
td
>
<
td
>
<
telerik:RadDatePicker
ID
=
"HireDatePicker"
DbSelectedDate='<%# Bind( "HireDate") %>'
runat="server" TabIndex="10">
</
telerik:RadDatePicker
>
</
td
>
</
tr
>
<
tr
>
<
td
>
Title:
</
td
>
<
td
>
<
asp:TextBox
ID
=
"TextBox4"
Text='<%# Bind( "Title") %>' runat="server" TabIndex="11">
</
asp:TextBox
>
</
td
>
</
tr
>
<
tr
>
<
td
>Check:</
td
>
<
td
>
<
asp:CheckBox
ID
=
"CheckBox1"
runat
=
"server"
/>
</
td
>
</
tr
>
</
table
>
</
td
>
<
td
>
</
td
>
</
tr
>
<
tr
>
<
td
align
=
"right"
colspan
=
"2"
>
<
asp:Button
ID
=
"btnUpdate"
Text='<%# (Container is GridEditFormInsertItem) ? "Insert" : "Update" %>'
runat="server" CommandName='<%# (Container is GridEditFormInsertItem) ? "PerformInsert" : "Update" %>'>
</
asp:Button
>
<
asp:Button
ID
=
"btnCancel"
Text
=
"Cancel"
runat
=
"server"
CausesValidation
=
"False"
CommandName
=
"Cancel"
></
asp:Button
>
</
td
>
</
tr
>
</
table
>
</
FormTemplate
>
</
EditFormSettings
>
</
MasterTableView
>
<
ClientSettings
>
<
ClientEvents
OnRowDblClick
=
"RowDblClick"
></
ClientEvents
>
</
ClientSettings
>
</
telerik:RadGrid
>
<
asp:SqlDataSource
ID
=
"SqlDataSource1"
runat
=
"server"
ConnectionString="<%$ ConnectionStrings:Northwind_newConnectionString3 %>"
DeleteCommand="DELETE FROM [Employees] WHERE [EmployeeID] = @EmployeeID"
InsertCommand="INSERT INTO [Employees] ([LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [Country], [HomePhone], [Notes], [ReportsTo]) VALUES (@LastName, @FirstName, @Title, @TitleOfCourtesy, @BirthDate, @HireDate, @Address, @City, @Region, @Country, @HomePhone, @Notes, @ReportsTo)"
SelectCommand="SELECT * FROM [Employees]" UpdateCommand="UPDATE [Employees] SET [LastName] = @LastName, [FirstName] = @FirstName, [Title] = @Title, [TitleOfCourtesy] = @TitleOfCourtesy, [BirthDate] = @BirthDate, [HireDate] = @HireDate, [Address] = @Address, [City] = @City, [Region] = @Region, [Country] = @Country, [HomePhone] = @HomePhone, [Notes] = @Notes WHERE [EmployeeID] = @EmployeeID">
<
DeleteParameters
>
<
asp:Parameter
Name
=
"EmployeeID"
Type
=
"Int32"
></
asp:Parameter
>
</
DeleteParameters
>
<
InsertParameters
>
<
asp:Parameter
Name
=
"LastName"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"FirstName"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Title"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"TitleOfCourtesy"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"BirthDate"
Type
=
"DateTime"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"HireDate"
Type
=
"DateTime"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Address"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"City"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Region"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Country"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"HomePhone"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Notes"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"ReportsTo"
Type
=
"Int32"
DefaultValue
=
""
></
asp:Parameter
>
</
InsertParameters
>
<
UpdateParameters
>
<
asp:Parameter
Name
=
"LastName"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"FirstName"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Title"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"TitleOfCourtesy"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"BirthDate"
Type
=
"DateTime"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"HireDate"
Type
=
"DateTime"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Address"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"City"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Region"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Country"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"HomePhone"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"Notes"
Type
=
"String"
></
asp:Parameter
>
<
asp:Parameter
Name
=
"EmployeeID"
Type
=
"Int32"
></
asp:Parameter
>
</
UpdateParameters
>
</
asp:SqlDataSource
>
</
div
>
</
form
>
</
body
>
</
html
>