RadUpload Returns Null

[Jonathan]

I have moved my application from one server to another. I am currently having an issue with the upload control on the new server.

I get a null reference exception when accessing.
RadUploadContext.Current.UploadedFiles

This returns a id
Response.Write(@"<script language='javascript'>alert('" + Request.QueryString["RadUrid"] + "');</script>");

Server setup
Windows 2008 R2
IIS 7.5

Thanks