Photoupload not working while in multiple updatepanel

In my project, in one of the page I have 2 update panel namely UP50 and UP37. The photoupload is within UP37. Now when both UP's are open, the photoupload  with UP37 is not working and says "no File Chosen'. If I remove the UP37 for Photoload, it is working and able to show using a 'showbutton'. Should I alter my code for UP37. Hereunder is my Code for UP37 raised after end of UP50.

<asp:UpdatePanel ID = "UpdatePanel37" runat="server"  UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="Panel117" runat="server"
        style="border-width: 1px; border-style: solid; top: 400px; left: 1185px; position: absolute; height: 161px; width: 279px; background-color:InactiveBorder; border-color:Black">

            <asp:Image ID="ImagePreview" runat="server" Height="97px" Width="99px"
            style="z-index: 1"/>
            <asp:FileUpload ID="PhotoUpload" runat="server"
              style="z-index: 1; left:100px; top: 53px; position: absolute; height: 46px; width: 218px; right: 90px;" />
           <asp:Button ID="Button7" runat="server" CausesValidation="False"
            onclick="Showbutton_Click"
            style="z-index: 1; left: 7px; top: 123px; position: absolute"
            Text="Show" />

</asp:Panel>

</ContentTemplate>
<Triggers>
<%--<asp:AsyncPostBackTrigger ControlID="Button3" EventName="Click" />--%>
<asp:PostBackTrigger ControlID="Button2" />
</Triggers>
</asp:UpdatePanel