为什么我的代码不能访问项目模板中的控件？

Question

我在模板字段中使用了面板，当我勾选复选框时它会消失。

我试过修理它但仍然消失了。代码在调试时运行良好，但显然不是。如果可以的话请帮忙。我已经花了很多时间在它上面。

代码：

                    <asp:TemplateField HeaderText='Finalized ?'>
                        <ItemTemplate>
                            <asp:LinkButton ID="btnFinalizedRecord" OnClick="btnFinalizedRecord_Click" runat="server" Text='<%# Convert.ToBoolean(Eval("IsFinalized")) == true? "Already Finalized": "Finalize" %>'
                                CssClass="" ToolTip="Finalize" CommandName="Finalize"
                                CommandArgument='<%#Eval("IsFinalized")%>' Enabled='<%# Convert.ToBoolean(Eval("IsFinalized")) == true? false: true %>'></asp:LinkButton>

                            <ajax:ConfirmButtonExtender ID="ConfirmButtonExtender1" runat="server" DisplayModalPopupID="mpe2" TargetControlID="btnFinalizedRecord">
                            </ajax:ConfirmButtonExtender>
                            <ajax:ModalPopupExtender ID="mpe2" runat="server" PopupControlID="pnlPopup2" TargetControlID="btnFinalizedRecord" OkControlID="btnYes"
                                CancelControlID="btnNo" BackgroundCssClass="modalBackground">
                            </ajax:ModalPopupExtender>
                            <asp:Panel ID="pnlPopup2" runat="server" CssClass="modalPopup" Style="display: none">
                                <div class="header">
                                    Confirmation
                                </div>
                                <div class="body">
                                    Are you sure to <b>Finalize</b>? 
                                    <asp:CheckBox ID="chkConfirmFinalize" runat="server" AutoPostBack="true" OnCheckedChanged="chkConfirmFinalize_CheckedChanged" />
                            <br />
                                    You will not be able to perform an edit after finalizing.
                                </div>                                        
                        <div class="Popupfooter" align="right">
                            <asp:Button ID="btnYes" Enabled="false" CssClass="btn btn-sm btn-danger" runat="server" Text="Yes" />
                            <asp:Button ID="btnNo" CssClass="btn btn-sm btn-primary" runat="server" Text="No" />
                        </div>
                            </asp:Panel>


                        </ItemTemplate>
                    </asp:TemplateField>

.cs代码：

 protected void chkConfirmFinalize_CheckedChanged(object sender, EventArgs e)
    {
        try
        {
            var chkConfirmFinalize = sender as CheckBox;
            GridViewRow gr = (GridViewRow)chkConfirmFinalize.NamingContainer;

            Panel pnlPopup2 = gr.FindControl("pnlPopup2") as Panel;

            if (chkConfirmFinalize.Checked == true)
            {
                btnYes.Visible = true;
            }
            else 
            {
                btnYes.Visible = false;
            }

            pnlPopup2.Visible = true;
        }
        catch (Exception ex)
        {
            Utility.Msg_Error(Master, ex.Message);
        }
    }