DragPanel won't work

Question

Hi all,
I was trying to user the DragPanel extender in my project but its not working, that is it wont allow me to drag the panel at run time.

Here is my code please tell me what am I missing

<asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:DragPanelExtender ID="DragPanelExtender1" runat="server" TargetControlID="pnlContainer" DragHandleID="pnlBody">
        </asp:DragPanelExtender>
        <asp:Panel ID="pnlContainer" runat="server">
            <asp:Panel ID="pnlBody" runat="server" BorderColor="Beige" BorderStyle="Solid">
                <asp:Label ID="Label1" runat="server" Text="This panel can be dragged anywhere in your window"></asp:Label><br />
                <asp:Label ID="Label2" runat="server" Text=""></asp:Label><br />
                <asp:Button ID="Button1" runat="server" Text="Update" onclick="Button1_Click" />
            </asp:Panel>
        </asp:Panel>