I am a newbie of boost and i want to use boost date_time library i have build the libboost_date_time.lib and boost_date_time.dll and put them in the lib path My devlope entironment is vc71 final beta+latest boost i get from cvs yesterday when i use some small code to test date_time_lib,i enconter with such error: error LNK2019: unresolved external symbol "public: char const * __thiscall boost::gregorian::greg_month::as_long_string(void)const " (? as_long_string@greg_month@gregorian@boost@@QBEPBDXZ) referenced in function "public: static class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl boost::date_time::month_formatter <class boost::gregorian::greg_month,class boost::date_time::simple_format>::format_month(class boost::gregorian::greg_month const &,class std::basic_ostream<char,struct std::char_traits<char> > &)" (?format_month @?$month_formatter@Vgreg_month@gregorian@boost@@Vsimple_format@date_time@ 3@@date_time@boost@@SAAAV?$basic_ostream@DU? $char_traits@D@std@@@std@@ABVgreg_month@gregorian@3@AAV45@@Z) code as follows: #ifndef DATE_TIME_INLINE #define DATE_TIME_INLINE #endif #include <boost/date_time/posix_time/posix_time.hpp> #include <iostream> using namespace boost::posix_time; int main(int , char*[] ) { std::cout << to_simple_string(second_clock::local_time()) << std::endl; } i use vc71 command line to compile anyone can tell me how to resolve such problems?thanks