need to add a reference to the Silverlight assembly in the <system.web><compilation><assemblies > section as follows; <add assembly=”System.Web.Silverlight, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35″ /> Add a new MIME type to allow Silverlight applications to run in your SharePoint web application. In IIS open the properties dialog for the SharePoint web application and select the