Open a user control in a pop up

I have a webform that contains a user control in a hidden div as follows
<div id="Dialog" style="display: none;"> <div class="DialogF"> <asp:UpdatePanel runat="server" ID="UpPanelDialog" UpdateMode="Conditional"> <ContentTemplate> <uc2:TabEmployee ID="Mine" runat="server"></uc2:TabEmployee> </ContentTemplate> </asp:UpdatePanel> </div> </div> I want to show that div/user control in a pop up from code behind, I tried this but It didn't work
this.Page.OpenDialog("Show", "Dialog");