I had the same problem..I have VS2010 express..
(Note: If you see this problem try checking references to EntityFramework.dll ..
May be it is missing.)
The following resolved it for me.
I installed latest MVC 3 Tools Update
then I installed EntityFramework 4.1
or using
NUGet ie. from with Visual Studio 2010 Express
(Tools->Library Package Manager -> Add library Package reference -> Select Online -> EntityFramework)
Strangely that didnt work..So i had to manually add a reference to "EntityFramework.dll"
try doing a search for the dll ..may be here
"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\"
If you already have it..just add a '.net' reference.
Note: If you use NuGet ,it creates a folder "packages" along side your Solution directory.
You will find the "EntityFramework.4.1.10331.0" folder inside it.Within "Libs" folder you will find
"EntityFramework.dll" .
Add reference to it using Browse tab and select the above dll.
