Hi, Please note that the first index works const hndl_index_type &h_type = boost::multi_index::get<hndl>(ns); NodePtrSet::const_iterator it = h_type.find(theHandle); //works but if I try to access the 2nd index doing: ... const group_index_type &g_type = boost::multi_index::get<group>(ns); NodePtrSet::iterator group_it = g_type.find(aGroup); I get the following output error: error C2440: 'initializing' : cannot convert from 'class boost::multi_index::detail::index_iterator<struct boost::multi_index::detail::ordered_index_node<struct boost::multi_index::detail::index_node_base<class boost::shared_ptr<class CtCAD::NodeBase> > > >' to 'class boost::multi_index::detail::index_iterator<struct boost::multi_index::detail::ordered_index_node<struct boost::multi_index::detail::ordered_index_node<struct boost::multi_index::detail::index_node_base<class boost::shared_ptr<class CtCAD::NodeBase> > > > >' No constructor could take the source type, or constructor overload resolution was ambiguous Any suggestions? Regards, Tal.Agmon