bairdo, how are you trying to load the roms? From the command line or through emulation station?
It would help if you would provide the exact command or emulation station’s relevant es_systems.cfg lines, such as:
If you’re using mame4all, the MAME roms need to be placed in the roms directory within mame4all. They won’t work in the RetroPie/roms/mame directory. You’ll also need to make sure to use %BASENAME% instead of %ROM% like above.