Word 2007 Documents.Open returns null in ASP.NET

Hi,In the following code the method Documents.Open returns null when running under ASP.NET, while running it in a console the code works fine. The computer is installed with Vista OS and Office 2007. The code works under ASP.NET on a windows 2000 server with Office 2003. (The website is configured with identity impersonate="true")Does anyone have any idea what is causing this?� � � � � � �  Object missing = Type.Missing;� � � � � � �  Application app = new Application();� � � � � � �  Object name = @"C:\a.doc";� � � � � � �  Object confirmConversions = false;� � � � � � �  Document doc = app.Documents.Open(� � � � � � � � � � �  ref name, ref confirmConversions,� � � � � � � � � � �  ref missing, ref missing, ref missing, ref missing,� � � � � � � � � � �  ref missing, ref missing, ref missing, ref missing,� � � � � � � � � � �  ref missing, ref missing, ref missing, ref missing,� � � � � � � � � � �  ref missing, ref missing� � � � � � �  );� � � � � � �  Object saveas = @"C:\b.doc";� � � � � � �  objec ...