I am Using model pop up in update panel..\[code\] <asp:updatepanel > <asp:ModelPopUpExtendar ID="Modelpop" TargetID="Panel1" /> </asp:updatePanel> <aspanel ID="panel1'> <asp:TextBox ID="txt" runat="server"></asp:TextBox> <asp:ImageButton ID="btn" runat="server" /> <cc1:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="txt" PopupButtonID="btn"></cc1:CalendarExtender> </aspanel>\[/code\].. The above things are my code.. in that while i click my image the pop up Extender is hiding .. when i use postback trigger for my Extender the calender also showing & pop up also not hiding.. But in my case i dont wanna use postback trigger...Thanks,SarathKumar