[Boost-users] Problem with shared_ptr

What's wrong with this code? When I push_back ptr to the vector, it pushes 0 instead of the value contained in ptr (which I checked and is non-zero). std::vector baseobjects = get_base_objects(path); std::vector result(get_base_objects.size()); BOOST_FOREACH (boost::shared_ptr<BaseClass> en, baseobjects) { boost::shared_ptr<DerivedClass> ptr = boost::dynamic_pointer_cast<DerivedClass>(en); //Error when push_back. Instead of ptr, I get 0 result.push_back(ptr); } Thanks.