Mocking LINQ DataContext (II)

This is a follow up from this thread: https://www.typemock.com/community/viewtopic.php?t=727

I have now downloaded version 4.2.4 so that I would be able to mock LINQ to SQL statements. But I am still having problems. Can you please advice me how to correctly mock these statements?

Below is my code under test:

      private Currencies()
      {
         loadCurrencies();
      }

      public static Currencies GetInstance()
      {
         if (_instance == null)
            _instance = new Currencies();
         return _instance;
      }

      private void getCurrencies()
      {
         Dictionary<string, Currency> tempList = new Dictionary<string, Currency>();

         using (Data.CurrencyModelDataContext db = new Data.CurrencyModelDataContext())
         {
            var currencies = from currency in db.CurrencyEntities
                         select currency;

            foreach (CurrencyEntity currency in currencies)
               tempList.Add(currency.CurrencyCode, new Currency(currency.CurrencyCode, currency.NoOfDecimals, currency.ReceiveIsAllowed, currency.SendIsAllowed, currency.ExchangeRate, currency.ExchangeRateUpdated));
         }

         _list.Clear();
         _list = tempList;
         _lastUpdated = DateTime.UtcNow;
      }

      private void loadCurrencies()
      {
         if (!refreshIsRequired())
            return;

         getCurrencies();
      }

and here is my test code:

      [TestMethod]
      public void GetInstance_NewInstance_RetrievesInstanceAndPopulatesCurrenciesFromDB()
      {
         Currency EUR = new Currency("EUR", 2, true, true, 1M, null);
         Currency USD = new Currency("USD", 2, true, true, 1.28M, DateTime.Now);
         var linqresult = new List<Currency>() { EUR, USD }.AsQueryable();

         CurrencyModelDataContext context = new CurrencyModelDataContext();
         using (RecordExpectations recorder = RecorderManager.StartRecording())
         {
            var mockedResult = from c in context.CurrencyEntities
                           select c;
            recorder.Return(linqresult);
         }

         Currency Expected = Currency.EUR;
         int expectedCount = 2;

         Currency Actual = Currencies.GetInstance()["EUR"];
         int actualCount = Currencies.GetInstance().Count;

         Assert.AreEqual(Expected, Actual, "Initialization of Currencies didn't populate proper currencies");
         Assert.AreEqual(expectedCount, actualCount, "Initialization of Currencies didn't populate with the two mocked currencies");
      }

This produces the following test error:

Test method Towah.Global.CurrencyServices.UnitTests.CurrenciesTest.GetInstance_NewInstance_RetrievesInstanceAndPopulatesCurrenciesFromDB threw exception: TypeMock.TypeMockException:
*** Cannot return a value for Expression.Lambda() because no value was set. use recorder.Return().
*** Note: Cannot mock types from mscorlib assembly..


I have tried various versions of mocking context.CurrencyEntities directly (but I am unable to create a System.Data.Linq.Table<CurrencyEntity>, so the linq statement following fails). The code I have put above is how I would ideally like it to work.

Any help in getting me educated in mocking LINQ statements is greatly appreciated.

Morten