I am using BinaryFormatter to serialize a collection of objects of class A stored in a System::Collections::Generic::List^.
The problem was that any objects referred to within child objects need not have been completely deserialized immediately after a GetValue call. In my case, the generic List had not yet been completely deserialized and so contained only null references. I finally used IDeserializationCallback to execute code after the object graph had been completely deserialized.