Hi Robert, With a class derived from DbObject and defined/implemented in my EXE (that use the DLL) I got archive_exception::unregistered_class. I tried to register it or to export it, but I could not make it work. *** So you put BOOST_CLASS_EXPORT(DbObject) in to a *.cpp file which is compiled as part of the exe? Yes, I do. Any Ideas? I use Version 1.38 of the library & VC8(2005). When I use BOOST_CLASS_TYPE_INFO(as in test_no_rtti.cpp sample ) for my EXE resident class, the ::get_key is never called. // get the eti record for the exported type "polymorphic_derived2" boost::serialization::extended_type_info const * const d2_eti = boost::serialization::extended_type_info::find( "polymorphic_derived2" ); works too before I start to serialize the collection. *** is this an attempt the issure raised above or is this a separate question. No separate question at all, this is the way I tried figure out if my class is really (and correctly) registered. Is this a correct way to test? How can I debug what's wrong? Thanks Andrei. _________________________________________________________________ News, entertainment and everything you care about at Live.com. Get it now! http://www.live.com/getstarted.aspx