There seems to be a conflict between ModalPopup and ValidationSummary. When both are used I get a JScript Error "Object Expected". The following code should reproduce the error:
<%@ Page Language="C#" %><%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><script runat="server">
protected void Button1_Click(object sender, EventArgs e)
{
CCSModalPopupExtender.Show();
}
protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
{
args.IsValid = true;
}
</script><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"><title>Untitled Page</title></head><body><form id="form1" runat="server"><asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><div><asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Show Alert" /><asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="Error" OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator><br /><asp:ValidationSummary ID="ValidationSummary1" runat="server" Width="632px" /><asp:Button ID="DummyCCSButton" runat="server" Text="Invisible" Style="display: none" /><cc1:ModalPopupExtender ID="CCSModalPopupExtender" runat="server" PopupControlID="CCStatePanel"
BackgroundCssClass="modalBackground" TargetControlID="DummyCCSButton" OkControlID="CCSOkButton"
DropShadow="true" PopupDragHandleControlID="CCSHeadPanel" RepositionMode="None"
BehaviorID="programmaticModalPopupBehavior"></cc1:ModalPopupExtender><asp:Panel ID="CCStatePanel" runat="server" Style="display: none"><asp:Panel ID="CCSHeadPanel" runat="server" Style="cursor: move; background-color: #DDDDDD;
border: solid 1px Gray; color: Black"><div style="text-align: center">
Header Text Here</div></asp:Panel><div><table cellpadding="5"><tr><td>
The message of the ModalPopup alert.</td></tr></table><p style="text-align: center;"><asp:Button ID="CCSOkButton" runat="server" Text="Close This" /></p></div></asp:Panel></div></form></body></html>