Sys.ArgumentNul lException: Value cannot be null. Parameter name: element

[pankajprakash]

Hi all

I am using the Ajax control toolkit and want to the fill the gridview but at the time of rendering it occurs the error "Sys.ArgumentNu llException: Value cannot be null. Parameter name: element". Here am posting the whole .ascx page.

Will you please let me know how can i remove this error.






<%@ Control Language="C#" AutoEventWireup ="true" CodeFile="ViewU sers1.ascx.cs" Inherits="Contr ols_ViewUsers1" %>
<%@ Register Assembly="AjaxC ontrolToolkit" Namespace="Ajax ControlToolkit" TagPrefix="ajax Toolkit" %>
<ajaxToolkit:To olkitScriptMana ger runat="Server" ID="ScriptManag er1" />
<style>
/*Modal Popup*/.modalBackgroun d
{
background-color: white;
filter: alpha(opacity=7 0);
opacity: 0.7;
}
</style>


<script type="text/javascript">
var styleToSelect;

// Add click handlers for buttons to show and hide modal popup on pageLoad
function pageLoad()
{

$addHandler($ge t("showModalPop upClientButton" ), 'click', showModalPopupV iaClient);
}

function showModalPopupV iaClient(ev)
{

alert(this.id );
document.getEle mentsByName("hd nDeleteID").val ue=this.id;

ev.preventDefau lt();
var modalPopupBehav ior = $find('programm aticModalPopupB ehavior');
modalPopupBehav ior.show();
}

function hideModalPopupV iaClient(ev)
{

ev.preventDefau lt();
var modalPopupBehav ior = $find('programm aticModalPopupB ehavior');
modalPopupBehav ior.hide();
}



</script>

<table width="100%" id="ParentTable ">
<tr>
<td>
<input type="hidden" id="hdnDeleteID " runat="server" />
<asp:Label ID="lblMessage " runat="server"> </asp:Label>
<asp:Label ID="lblGridMess " runat="server" />
<asp:GridView ID="gvUsers" Width="100%" runat="server" AllowPaging="Tr ue" AutoGenerateCol umns="False"
DataKeyNames="I D" OnPageIndexChan ging="gvUsers_P ageIndexChangin g" AllowSorting="t rue"
OnRowCommand="g vUsers_RowComma nd" OnRowDataBound= "gvUsers_RowDat aBound" PagerStyle-HorizontalAlign ="left"
OnSorting="gvUs ers_Sorting" OnRowDeleting=" gvUsers_RowDele ting">
<Columns>
<asp:TemplateFi eld Visible="False" >
<ItemTemplate >
<asp:Label ID="lbl" runat="server" Text='<%#Eval(" Email")%>'></asp:Label>
</ItemTemplate>
</asp:TemplateFie ld>
<asp:BoundFie ld DataField="ID" HeaderText="Use r ID" Visible="False" />
<asp:TemplateFi eld HeaderText="Fir stName" SortExpression= "FirstName" >
<ItemTemplate >
<%#Eval("FName" ) %>
</ItemTemplate>
<ItemStyle Width="15%" HorizontalAlign ="Left" />
<HeaderStyle HorizontalAlign ="Center" />
</asp:TemplateFie ld>
<asp:TemplateFi eld HeaderText="Ema ilAddress" SortExpression= "Email">
<ItemTemplate >
<%#Eval("Email" ) %>
</ItemTemplate>
<ItemStyle Width="30%" HorizontalAlign ="Left" />
<HeaderStyle HorizontalAlign ="Center" />
</asp:TemplateFie ld>
<asp:TemplateFi eld>
<ItemTemplate >
<a href='' name='<%#Eval(" ID") %>' id='<%#Eval("ID ") %>' onclick='javasc ript:$addHandle r($get(this.id) , "click", showModalPopupV iaClient);'>
Edit</a>
<%--<a href="#" name='<%#Eval(" ID") %>' onclick="javasc ript:return GetUserData('<% #Eval("ID")%>') " >Edit</a>--%>
</ItemTemplate>
</asp:TemplateFie ld>
<asp:TemplateFi eld ShowHeader="Fal se">
<ItemTemplate >
<%--<asp:LinkButt on ID="LinkButton1 " runat="server" CausesValidatio n="False" CommandName="De lete"
CommandArgument ='<%#Eval("ID") %>' Text="Delete"></asp:LinkButton>--%>
<a href='' name='<%#Eval(" ID") %>' id='<%#Eval("ID ") %>' onclick='javasc ript:$addHandle r($get(this.id) , "click", showModalPopupV iaClient);'>
Delete</a>
</ItemTemplate>
</asp:TemplateFie ld>
</Columns>
<PagerStyle HorizontalAlign ="Left" />
</asp:GridView>
</td>
</tr>
<tr>
<td>
<div class="demoarea ">
<br />
<asp:Button runat="server" ID="hiddenTarge tControlForModa lPopup" Style="display: block"
Visible="false" />
<ajaxToolkit:Mo dalPopupExtende r runat="server" ID="programmati cModalPopup" BehaviorID="pro grammaticModalP opupBehavior"
BackgroundCssCl ass="modalBackg round" TargetControlID ="hiddenTargetC ontrolForModalP opup"
PopupControlID= "programmaticPo pup" DropShadow="Tru e" PopupDragHandle ControlID="prog rammaticPopupDr agHandle"
RepositionMode= "RepositionOnWi ndowScroll">
</ajaxToolkit:Mod alPopupExtender >
<asp:Panel runat="server" ID="programmati cPopup" Style="display: none; width: 350px;
padding: 10px" BackColor="Whit e">
<asp:Panel runat="Server" ID="programmati cPopupDragHandl e" Style="cursor: move; background-color: #DDDDDD;
border: solid 1px Gray; color: Black; text-align: center;">
User</asp:Panel>
<table width="200px">
<tr>
<td align="left">
Delete User
</td>
</tr>
<tr>
<td align="center">
Are you sure to delete the user?
</td>
</tr>
<tr>
<td align="center">
<asp:Button ID="btnOk" runat="server" Text="OK" OnClick="btnOK_ Click" />
<asp:Button ID="btnCancel" runat="server" Text="Cancel" OnClick="btnCan cel_Click" />
</td>
</tr>
</table>
</asp:Panel>
</div>
</td>
</tr>
</table>