[boost] result_of?

I replaced my home grown result_type<> with boost::result_of<> today only to find that I couldn't get it to work. When I try to use result_of with VC 7.1: struct test_struct { typedef int result_type; }; boost::result_of<test_struct>::type i = 5; I get: test.cpp(10) : error C2027: use of undefined type 'boost::result_of<F>' I get the same results if I use function types of pointer to function types: boost::result_of<int (*)()>::type i = 5; boost::result_of<int ()()>::type i = 5; Am I missing something? Thanks, Brock Peabody