Hi, I just got a strange compiling error while testing Msm with VC8. If I write: template <class StateType> typename ::boost::enable_if< typename ::boost::mpl::and_<typename ::boost::mpl::not_ <typename has_exit_pseudo_states<StateType>::type>::type, typename ::boost::mpl::not_ <typename is_pseudo_exit<StateType>::type>::type >::type,BaseState*>::type I get : error C2770: invalid explicit template argument(s) for '`global namespace'::boost::enable_if<is_pseudo_exit<StateType>::type,BaseState*>::type boost::msm::state_machine<Derived,HistoryPolicy,BaseState>::add_state<ContainingSM>::new_state_helper(boost::msm::dummy<__formal>) const' If I replace the ::boost::mpl by boost::mpl, it compiles fine. But I'm still wondering if I'm doing something wrong or the compiler. Does anyone have an answer? Thanks in advance, Christophe