ASP.net Webpage using AJAX works on one IIS server but another

I have a simple ASP webpage using the AJAX Controltoolkit.  I published to a dev IIS server and the AJAX control works fine, but when I publish the same project to a different IIS (production) the AJAX control does not update.  

I have a simple Label on the page that is displaying the current datetime that updates every second via server side Timer1_Tick event

Both servers are running Win Server 2012 R2 and IIS (version 8.5.9600)

here is the snippet of code showing the Timer1 and label:

               <td class="auto-style13">                  
                     <asp:ScriptManager ID="ScriptManager1"
                        runat="server">
                    </asp:ScriptManager>
                    <asp:Timer ID="Timer1" runat="server" Interval="1000" OnTick="Timer1_Tick">
                    </asp:Timer>
                    <asp:UpdatePanel ID="UpdatePanel1"
                        runat="server">
                        <ContentTemplate>
                            <asp:Label ID="Label2" runat="server" Text="Current DateTime : " ForeColor="Gray"></asp:Label>
                            <asp:Label ID="CurrentDateTime" runat="server"
                            ForeColor="Gray" BorderStyle="Inset" BorderWidth="1px" Font-Size="Medium" >Label2</asp:Label>
                        <br />
                        </ContentTemplate>
                        <Triggers>
                            <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick"></asp:AsyncPostBackTrigger>
                        </Triggers>
                    </asp:UpdatePanel>      
                </td>

I have compared the two IIS configurations but cannot figure out why the page works on one server but not the other?