[Boost-users] serializing abstract base class

I'm trying to serialize an abstract base class. I used the BOOST_IS_ABSTRACT macro, but the compile fails with the following error... public/dataclasses/I3Particle.h:225: syntax error before `namespace' public/dataclasses/I3Particle.h:225: syntax error before `}' token line 225 of I3Particle is... BOOST_IS_ABSTRACT(I3Particle); Is is not as simple as adding this one line? I'm using gcc 3.2.3. Thanks, Alex.