[Boost-users] boost::serialization problem, derived class through shared_ptr

I'm trying to serialize a derived class through a shared_ptr<> to the base class. I'm getting an unregistered class exception even though my derived class is registered with register_type<>. It seems the exception is being thrown while trying to serialize boost::detail::sp_counted_base which I believe is part of shared_ptr. Could this be an internal error in the serialization library?