ASP.Net AjaxControlkit - ModalPopupExtender - panel won't close

[ZeK005]

I have a ModalPopupExtender control which is opened via a LinkButton on a GridView:\[code\]<asp:LinkButton ID="btnAssocCampusPopup" runat="server" OnClick="lnkbtnOpenCampusPopup_Click" Text='<%# Eval("NumberOfAssociatedCampuses").ToString() %>'></asp:LinkButton>\[/code\]The click event opens the Popup (works fine) like so:\[code\] protected void lnkbtnOpenCampusPopup_Click(object sender, EventArgs e) { updpnlSchoolCampusAssign.Update(); popupAssignCampus.Show(); }\[/code\]And here is the extender code:\[code\]<asp:ModalPopupExtender ID="popupAssignCampus" runat="server" PopupControlID="pnlAssignCampus" TargetControlID="pnlAssignCampus" CancelControlID="btnCampusClose" BackgroundCssClass="modalBackground"></asp:ModalPopupExtender><aspanel runat="server" ID="pnlAssignCampus" CssClass="modalPopup" style="display:none"> <asp:UpdatePanel ID="updpnlSchoolCampusAssign" runat="server" UpdateMode="Conditional"> <ContentTemplate> </ContentTemplate> </asp:UpdatePanel> <asp:Button ID="btnCampusClose" runat="server" Text="Close" OnClick="btnCampusClose_Click"/></aspanel>\[/code\]As you can see I have the CancelControlID set, but I've also tried a "hide()" method via javascript, and also added a click event server side to the btnCampusClose, none of these works. When I run Firebug, there is something strange going on where it looks like the script sets "display:none" on the div, and then immediately erases it. Very strange.