You have set the property Visible="false" for the Panel in this line of the code
<asp:panel id="Panel1" runat="server" height="295px" width="687px" visible="False" xmlns:asp="#unknown"></asp:panel>
You need to remove it....
<asp:panel id="Panel1" runat="server" height="295px" width="687px" xmlns:asp="#unknown"></asp:panel>
Visible="false" does not render the Panel on the client side