I know I've had this problem when I started working with Silverlight, but I can't for the life of me remember how to fix it.
I created a new RIA service application using the standard tutorial, added a table from the database and added a grid to display the results. Works great. Now I pull open the Web properties and change the web project to "use local IIS Web server". Suddenly the application will load up and give me the friendly "NotFound" error.
Please, someone remind me what I'm missing here.