FileUpload.HasFile is always False

Hi,

I have a WebUserControl which has a FileUpload control. This control has some UI logic which hides/shows parts of the UserControl. The page which host this UC has an Ajax Update Panel. When I try to uplaod a file the FileUpload1.HasFile is always set to false! Any idea why? I have the viewstate set to true as well but no idea why this happens?!

Thanks
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