Hello, in the example attached I've got the compiler error base_from.cpp: In constructor ‘header_fixture::header_fixture()’: base_from.cpp:48: error: type ‘client::detail::header_grammar<boost::spirit::karma::detail::output_iterator<const char*, mpl_::int_<15>, boost::fusion::unused_type> >’ is not a direct base of ‘header_fixture’ /home/olaf/Projects/programming/cpp/boost/trunk/boost/utility/base_from_member.hpp:69: error: ‘client::detail::string_grammar<boost::spirit::karma::detail::output_iterator<const char*, mpl_::int_<15>, boost::fusion::unused_type> > boost::base_from_member<client::detail::string_grammar<boost::spirit::karma::detail::output_iterator<const char*, mpl_::int_<15>, boost::fusion::unused_type> >, 0>::member’ is protected where the 2nd error is due to the 1st one. Why does it not work? without karma::grammar it compiles. How to fix it? Thanks, Olaf