This was originally posted to the Silverlight forum. I was advised that since this might be an ASP.NET problem I should post it here too. Hi, I am having difficulty deploying a Silverlight 4 RIA services Web app to IIS 6 on Windows Server 2003. The application works fine when running on the development server. However, when deployed to a production server, all the Web service calls redirect to the login page. Here are the details: The site uses forms authentication. Login is via an ASP.NET Web page; the Silverlight application does not have its own version of the login page. Login is working correctly. Even browsing to the virtual ".svc" page redirects to the login page. Using the service trace viewer, an "Authentication failed for HTTP(S) connection" message is visible. (We're not using SSL.)