OK, I missed completely that you are working with a combat simulator, CFS2? What I mentioned above is for FSX. I am using FSDSv3.51 which doesn't compile for CFS2. I don't have FSDSv2 installed so I don't recall how one got to a .bgl file. In fact, I didn't do a scenery object until FSDSv3 which used Makemdl as the compiler and it still worked like I said above, just a different compiler.
Sorry, Paul