LINQ Query Problems

Hi,

I'm trying out some of the new LINQ code and trying to use TypeMock with it. I have 4.1 install. But I keep getting an error.

Error Message

Test method Controller2008.Test.ProductControllerTest.GetCategoriesTest threw exception: TypeMock.TypeMockException:
*** Cannot return a value for ProductsDataContext.get_Categories() because no value was set. use recorder.Return().
*** Note: Cannot mock types from mscorlib assembly..

Unit Test Method

        [TestMethod()]
        [ClearMocks]
        [VerifyMocks]
        public void GetCategoriesTest()
        {
            ProductController target = new ProductController();
            List<Category> expected = new List<Category>(){
                new Category { CategoryID = 1, CategoryName = "Test1", Description = "Testing1"},
                new Category { CategoryID = 2, CategoryName = "Test2", Description = "Testing2"},
                new Category { CategoryID = 3, CategoryName = "Test3", Description = "Testing3"}
            };
            List<Category> actual;

            var dummyData = new[] {new { CategoryID = 1, CategoryName = "Test1", Description = "Testing1"},
                                   new { CategoryID = 2, CategoryName = "Test2", Description = "Testing2"},
                                   new { CategoryID = 3, CategoryName = "Test3", Description = "Testing3"}};

            ProductsDataContext db = new ProductsDataContext();

            using (RecordExpectations recorder = RecorderManager.StartRecording())
            {
                var query = from cat in db.Categories  //**Breaks on this line.
                            select cat;

                recorder.Return(dummyData);
            }

            actual = target.GetCategories();
            
            Assert.AreEqual(expected, actual);
        }

Do I need to have the enterprise version to run this code? I'm using the Professional version.

Thanks,
Eric