Entity framework error "Entity type is not mapped."

Have you tried representing it using a Complex Type instead of an Entity and mapping to that instead?

http://msdn.microsoft.com/en-us/library/bb738472.aspx

1. Open the datamodel (edmx file)
2. Right-click in the datamodel and select Model Browser
3. In the model browser window go to Function Imports and delete the appropriate items.

Each entity must be mapped either to QueryView or to database table / defining query. You can't create the entity which is not mapped at all. If you want to define result of function import which is not mapped in your model you must define your VendorBrief as complex type.

Try to open your Entity file diagram, the .edmx. And then delete all the tables using DEL. And then right click inside the diagram and select Update Model from Database.

The Visual Studio is a little bugged in this stuff.