Modal Popup Extender Panel is always visible

Hi all

I have a  ModalPopupExtender with a popup panel that is shown and hidden according to the ModalPopupExtender OkControlID and everything is working fine.

When I added a Crystal report viewer, then the popup panel didnot work as before:

• It didn't disappear from the page when the page loads
• It is always visible
• The CancelControlID doesn't hide the popup panel.

The html code is:

<CR:CrystalReportViewer ID="crv1" runat="server" AutoDataBind="true" Height="50px" Width="350px" /><asp:ImageButton ID="imbSow1" runat="server" ImageUrl="../images/ThumbSow1.png" /><asp:Panel ID="pnlPreview" runat="server" BorderStyle="Solid" BorderColor="Black" CssClass="mpePreview"><div style="width: 350px; height: 350px; background-color: aqua; margin: 100px auto;"><asp:Button runat="server" Text="موافق" ID="btnOK" /></div></asp:Panel><ajaxToolkit:ModalPopupExtender ID="mpePreview" runat="server" TargetControlID="imbSow1" PopupControlID="pnlPreview" OkControlID="btnOK" CancelControlID="btnOK" ></ajaxToolkit:ModalPopupExtender>

If I remove the Crystal report viewer , everything works fine.

I got mad with it.