Unable to access controls in code behind when i use in RadPanel Bar

[Sankar]

<asp:UpdatePanel runat="server" ID="upZipCodes" UpdateMode="Conditional">
        <ContentTemplate>
            <br />
            <br />
            <telerik:RadAjaxPanel ID="GeoTarget" runat="server">
                <telerik:RadPanelBar runat="server" ID="trpbGeoTarget" ExpandMode="SingleExpandedItem">
                    <Items>
                        <telerik:RadPanelItem Expanded="True" Text="Discreate ZipCodes List" runat="server"
                            Selected="true">
                            <Items>
                                <telerik:RadPanelItem Value="DiscreateZipCodes" runat="server" Expanded="true">
                                  <ItemTemplate>

                                   <div class="text" style="background-color: #edf9fe">
                                  <asp:Panel runat="server" ID="pnlDiscrete">
                                        <table border="1" style="width: 790px; height: 476px;">
            <tr>
                <td class="style17">
                    <asp:Label ID="Label4" runat="server" SkinID="InputRegular">Discrete List:</asp:Label>
                </td>
            </tr>
            <tr>
                <td class="style26">
                    <asp:Button ID="btnAddAll" runat="server" OnClick="btnAddAll_Click" Style="z-index: 1;
                        left: 83px; top: 2px; position: relative; width: 105px; height: 26px;" Text=" Add ZipCodes "
                        ToolTip="Click here to Add zipcode in List" />
                          <asp:Button ID="btnClearList" runat="server"
                        OnClick="btnClearList_Click" Style="z-index: 1; top: 3px; position: relative;
                        width: 74px; left: 175px" Text="Clear List" ToolTip="It Removes all ZipCode from List" />

                </td>
            </tr>
            <tr>
                <td align="left">
                    <asp:TextBox ID="txtZipCode" runat="server" Height="47px" SkinID="Long" TextMode="MultiLine"
                        ToolTip="Enter ZipCodes" Width="454px"></asp:TextBox>
                    <uc2:Helper ID="Helper3" runat="server" ResourceKey="ZipCode" />
                    <ajaxToolkit:FilteredTextBoxExtender ID="Validatior" runat="server" FilterType="Custom, Numbers"
                        TargetControlID="txtZipCode" ValidChars="," />
                    <asp:RequiredFieldValidator ID="rfvZip" runat="server" ControlToValidate="txtZipCode"
                        Display="Dynamic" ErrorMessage="* Enter Comma Sepertaed ZipCodes" SetFocusOnError="true"
                        SkinID="ClientMessaging"></asp:RequiredFieldValidator>
                </td>
            </tr>
            <tr>
                <td align="left">
                    <asp:Panel ID="pnlGeoTargetProfile" runat="server" ScrollBars="Both">
                        <asp:GridView ID="grdZipDiscreateList" runat="server" AutoGenerateColumns="False"
                            DataKeyNames="ZipCode" EnableModelValidation="True" RowStyle-Height="1px" ShowFooter="True"
                            SkinID="view" Width="779px" AllowPaging="True" overflow="auto" ScrollBars="Both">
                            <Columns>
                                <asp:BoundField DataField="ZIPCode" HeaderText="ZipCode" ReadOnly="true" />
                                <asp:BoundField DataField="City" HeaderText=" City Name" ReadOnly="true" />
                                <asp:BoundField DataField="State" HeaderText="State" ReadOnly="true" />
                                <asp:TemplateField HeaderText="Action" ItemStyle-HorizontalAlign="Center">
                                    <ItemTemplate>
                                        <asp:Panel ID="pnlDelete" runat="server">
                                            <asp:LinkButton ID="lnkRemove" runat="server" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "ZIPCode") + "," + DataBinder.Eval(Container, "RowIndex") %>'
                                                OnClientClick="return confirm('Are you remove want to remove this ZipCode from the Discrete list ? Do you wish to continue.');"
                                                Text="Remove"><img alt="" src="../Images/Icons/remove.png" border="0" title="remove"></asp:LinkButton>
                                        </asp:Panel>
                                    </ItemTemplate>
                                    <ItemStyle HorizontalAlign="Center" />
                                </asp:TemplateField>
                            </Columns>
                            <RowStyle Height=".5px" />
                        </asp:GridView>
                    </asp:Panel>
                </td>
            </tr>
            <tr>
                <td>
                     <asp:Button ID="btnSave" runat="server" SkinID="btnSave" Text=" Updates ZipCodes "
                        ToolTip="Click here to Update zipcodes in List" ValidationGroup="ClientDegree"
                        Width="157px" />
                    <asp:Button ID="btnCleargrid" runat="server" OnClick="btnCleargrid_Click" Style="z-index: 1;
                        left: 140px; top: 0px; position: relative; width: 133px; height: 26px" Text="Delete All ZipCodes"
                        ToolTip="It Removes all ZipCode from List" />
                    <asp:Button ID="btnClose" runat="server" OnClick="btnClose_Click" Style="z-index: 1;
                        left: 186px; top: 0px; position: relative; width: 52px; height: 26px" Text="Close" />

                </td>
            </tr>
        </table>

    </asp:Panel>
                                    </div>
                                        <ul class="formList" id="accountInfo">
                                  </ItemTemplate>
                                 </telerik:RadPanelItem>
                            </Items>
                        </telerik:RadPanelItem>
                        <telerik:RadPanelItem Expanded="True" Text="States List" runat="server" Selected="true">
                            <Items>
                                <telerik:RadPanelItem Value="States List" runat="server">
                                    <ItemTemplate>
                                        <div class="text" style="background-color: #edf9fe">
                                        </div>
                                        <ul class="formList" id="accountInfo">
                                            <asp:Panel runat="server" ID="pnlStateList">
                                                <table border="1">
                                                    <tr>
                                                        <td class="style15">
                                                            <uc1:campus ID="campus" runat="server" />
                                                        </td>
                                                    </tr>
                                                </table>
                                            </asp:Panel>
                                    </ItemTemplate>
                                </telerik:RadPanelItem>
                            </Items>
                        </telerik:RadPanelItem>
                        <telerik:RadPanelItem Expanded="True" Text="ZipCodes Within Radius" runat="server"
                            Selected="true">
                            <Items>
                                <telerik:RadPanelItem Value="ZipCodes in Radius" runat="server">
                                    <ItemTemplate>
                                        <ul class="formList" id="accountInfo">
                                            <asp:Panel ID="pnlMiles" runat="server">
                                                <table border="1">
                                                    <tr>
                                                        <td class="style25">
                                                            <asp:Label ID="lblZipCodes" runat="server" Text="ZipCodes within: "></asp:Label>
                                                            <asp:TextBox ID="txtMiles" runat="server" Width="32px"></asp:TextBox><asp:RequiredFieldValidator
                                                                ControlToValidate="txtMiles" ID="RequiredFieldValidator3" runat="server" Display="Dynamic"
                                                                ErrorMessage="* Enter Miles" SetFocusOnError="true" SkinID="ClientMessaging"
                                                                ValidationGroup="ClientDegree"></asp:RequiredFieldValidator>
                                                            <asp:Label ID="lblMilesOfRadious" runat="server" Text="Miles Of Radius: "></asp:Label>
                                                            <asp:TextBox ID="txtZipInMiles" runat="server" Width="90px"></asp:TextBox>
                                                            <uc2:Helper ID="Helper4" runat="server" ResourceKey="ZipCode" />
                                                            <asp:RequiredFieldValidator ControlToValidate="txtZipInMiles" ID="RequiredFieldValidator4"
                                                                runat="server" Display="Dynamic" ErrorMessage="* Enter Numric ZipCodes" SetFocusOnError="true"
                                                                SkinID="ClientMessaging" ValidationGroup="ClientDegree"></asp:RequiredFieldValidator>
                                                            <ajaxToolkit:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server"
                                                                FilterType="Custom, Numbers" TargetControlID="txtZipInMiles" ValidChars="," />
                                                        </td>
                                                    </tr>
                                                </table>
                                            </asp:Panel>
                                    </ItemTemplate>
                                </telerik:RadPanelItem>
                            </Items>
                        </telerik:RadPanelItem>
                    </Items>
                    <CollapseAnimation Duration="100" Type="None" />
                    <ExpandAnimation Duration="100" Type="None" />
                </telerik:RadPanelBar>
            </telerik:RadAjaxPanel>
            <%--  <Items>
                <telerik:RadPanelItem Text="Discrete List Of ZipCodes" Expanded="True">
                    <Items>
                        <telerik:RadPanelItem Text="Personal Folders" />

                    </Items>--%>
            <br />
            <br />
        </ContentTemplate>
    </asp:UpdatePanel>

I am unable to access my controls in my code behind and when i am trying to access my Controls i am getting an  error of "Controls are not existing in current context".
I have attached my error file. I have very basic understanding of rad panal Bar. So can you please explin me in detail what the ploblem is.?
Thanks in advance.

[Shinu]

Hello Ramon,

You can try the following code snippet to locates the TextBox in the  Button_click event handler.
C#:

protected void btnAddAll_Click(object sender, EventArgs e)
 {
     Button btn = sender as Button;
     TextBox txtbx = btn.Parent.FindControl("txtZipCode") as TextBox;
     txtbx.Text = "hai";
 }

The following documentation shows more information on this.
Accessing Controls Inside Templates

Thanks,
Shinu.

[Sankar]

thanks, it works.