I also tried it, but nope didnt work on my x50v either
You could try
PocketCultMame wich claims to work with some neogeo roms
(didn't work for me either, and believe me, I tried many versions of different neogeo roms, maybe someone got a tip using this emulator with neogeo roms

).
Only solution for me was installing an
psx emu and an metal slug x iso, the result is amazing (full fps with sound, and the iso is "only" 99,4mb)