Hey – so I feel like a total moron, but I’m having a huge issue with loading roms in MAME in my pi.

I just put retro-pi on, and it is up and running. I have tried 3 different rom versions of galaga (the whole reason I am building the arcade) and none of them are working. I am putting the files into the “mame” folder under the roms subdirectory. They show up, but won’t run. I don’t know whether this is the directory for advMAME or mame4all-pi, or both.
– edit: have used the 0.37b5 rom, as well as other versions and none will load

If someone could help me out with troubleshooting this I would really appreciate it