Using The UpdateProgress And PostBackTrigger?

I have a project where I'm using the 'FileUpload' Control in an update panel. In order to make the control work correctly I needed to add a 'PostBackTrigger' for the button that is used to process the file from the FileUpload control. That all works fine other than the program processes a lot of data and needs a progress bar to show the user that its still working. I have tried using the Ajax 'UpdateProgress' control but it will not work when the button (causing the Async post) has a PostBackTrigger associated with it.

Note: if you take off the Trigger, the UpdateProgress works just fine but the FileUpload fails. I have run into this issue before with the FileUpload control.Here is a simple example

<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

[code].....