R_TextureNumForName

I modified a level using DoomBuilder, but every time I try to run it in doom2.exe (for my old networked computers) i get the error "R_TextureNumForName: not found", I have tried some different error checkers, and fixed the problems given by them, but i still get this error. How do I fix this, besides using a port? Thanks

This wad uses new textures?

Nevermind, had a missing texture.

That's what I like about Boom-derived ports: those mention the actual texture name missing. Gods, that saved me a lot of frustration :)