Hello All, I have got the following warning 1>boost\boost_1_44_0\boost\mpl\print.hpp(51): warning C4308: negative integral constant converted to unsigned type 1> boost\boost_1_44_0\boost\serialization\static_warning.hpp(92) : see reference to class template instantiation 'boost::mpl::print<T>' being compiled 1> with 1> [ 1> T=boost::serialization::BOOST_SERIALIZATION_STATIC_WARNING_LINE<137> 1> ] 1> boost\boost_1_44_0\boost\archive\detail\check.hpp(137) : see reference to class template instantiation 'boost::serialization::static_warning_test<B,L>' being compiled 1> with 1> [ 1> B=false, 1> L=137 1> ] 1> boost\boost_1_44_0\boost\archive\detail\oserializer.hpp(453) : see reference to function template instantiation 'void boost::archive::detail::check_pointer_level<T>(void)' being compiled 1> with 1> [ 1> T=std::set<double> 1> ] during serialization of boost:shared_ptr<std::set<double>> (the same also e.g. for boost:shared_ptr<std::vector<double>>) My compiler is MS Visual Studio 2010. Boost version: 1.44 The serialization of std::set<double> (or std::vector<double>) works fine. What is wrong? Should the tracking really be changed to track_always? Kind Regards, Andreas