Destructing an object

Question

Hi, I have this main "test" code, { Firm f = new Firm(0.3f); Consumer c = new Consumer(1,f); Console.WriteLine("First Test {0}",(c.isNull() ? "FAIL" : "OK")); f = null; GC.Collect(); GC.WaitForPendingFinalizers(); Console.WriteLine("Second Test {0}",(c.isNull() ? "OK" : "FAIL")); } The Consumer constructor do this... public Consumer(int pId, Firm pFirm) { Id = pId; myFirm = new Firm(0f); myFirm = pFirm; } where myFirm is defined as "private Firm myFirm;" and the isNull() method is like this, public bool isNull() { return (myFirm==null); } When I run the test... y obtain, First Test OK Second Test FAIL Can anyone explain to me why the second test Fail? I understand (well I think so) that the object "f" is passed to the constructor by reference. Thanks in advance!!!!