[Boost-users] serialization

has anyone seen this compile error before, and know how to fix it? /usr/local/include/boost-1_32/boost/archive/detail/iserializer.hpp:428: no type named `type' in `struct boost::mpl::eval_if::abstract<MyClass> >, boost::mpl::identity::non_abstract<MyClass> > >' im trying to serialize a polymorphic class that has a pointer to another class of the same type in it. if i comment out that line in the serialization function, the error goes away.