file uploader is not completed its progressbar its stoped at 98% using ajax control in asp.net

<asp:Button ID="btnUpload" runat="server"
Text="Upload File"/>
<asp:ModalPopupExtender runat="server"
ID="modelPopupExtender1"
TargetControlID="btnUpload"
PopupControlID="popUpPanel"
OkControlID="btOK"
BackgroundCssClass="modalBackground">

<asp:Panel ID="popUpPanel" runat="server" CssClass="pnl">



<asp:Label ID="lblMessage" runat="server"/>


<asp:Button ID="btOK" runat="server" Text="OK" />
<asp:LinkButton ID="LinkButton1" runat="server" CssClass="close"
OnClientClick="$find('modelPopupExtender1').hide(); return false;"/>



my .cs code is-------Ajax control is stopped at 98% to its progress bar and file is not upload.using ajax control in asp.net....plzzz help me...

protected void AjaxFileUpload1_UploadComplete(object sender, AjaxControlToolkit.AjaxFileUploadEventArgs e)
{
try
{
string path = Server.MapPath("~/worker/DiffImage") + e.FileName;
AjaxFileUpload1.SaveAs(path);
}
catch (Exception)
{ }

}