[Demeter-main] Linking error when inheriting TerrainTextureFactory

Ok, We have a class TerrainTextureFactory : public =
Demeter::TextureFactory;

When linking in msvc6 i get:

error LNK2001: unresolved external symbol "public: virtual void =
__thiscall Demeter::TextureFactory::GenerateTextureCell(class =
Demeter::Terrain *,class Demeter::TextureCell =
*,float,float,float,float)"

even though its present in terrain.cpp.  If i overide the function in =
our implementation I still get the linking
error..

Any thoughts?

Dave.