Modelpopup extender показывает ошибку

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Modelpopup extender showing below script error 

Uncaught TypeError: Cannot read property '_events' of null
    
at Sys.UI.DomEvent.addHandler (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
    
at AjaxControlToolkit.ModalPopupBehavior.initialize (ScriptResource.axd?d=jgdlKh2MJXzFMdkd3f91tVrb_Pps7ZOWCLcBucCntGpYKcBXsTg6wzQ4A2HSbQ-djIn0K9QGPlc9HQ…:1)
    
at AjaxControlToolkit.ModalPopupBehavior.endUpdate (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
  
  at Sys.Component.create (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
    
at Array.<anonymous> (GenerateInvoice.aspx:1040)
    at ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5
  
  at Sys._Application._raiseInit (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
  
  at Sys._Application.initialize (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
    
at b (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)
    
at HTMLDocument.a (ScriptResource.axd?d=co5QUPy2Hub1TZ9kFn66FaXSuHubiNR6E4Wd-9hfFsA_PvE4i61VYpBo1xSbRUtPX7PuVHKiRDqCYe…:5)

Что я уже пробовал:

Я уже сделал это-

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" EnablePartialRendering="true" ScriptMode="Release" AsyncPostBackTimeout="100">
            
                    </asp:ScriptManager>

<asp:LinkButton ID="lnkFake" runat="server" />
                        <asp:ModalPopupExtender ID="mpeTimeout" BehaviorID="mpeTimeout" runat="server" PopupControlID="pnlPopup"
                            TargetControlID="lnkFake" OkControlID="btnYes" CancelControlID="btnNo" BackgroundCssClass="modalBackground"
                            OnOkScript="ResetSession()">
                        </asp:ModalPopupExtender>
                        <asp:Panel ID="pnlPopup" runat="server" CssClass="modalPopup" Style="display: none">
                            <div class="header">
                                Session Expiring!
                            </div>
                            <div class="body">
                                Your Session will expire in <span id="seconds"></span> seconds.<br />
                                Do you want to reset?
                            </div>
                            <div class="btnSection" align="right">
                                <asp:Button ID="btnYes" runat="server" Text="OK" CssClass="yes" />
                               <%-- <asp:Button ID="btnNo" runat="server" Text="No" CssClass="no" />--%>
                            </div>
                        </asp:Panel>

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