Firstly, I'm a bit of a retro gaming newbie, so forgive me for being ignorant!
I'm running MAME Plus (0.129), and so far I've downloaded about 20 roms. I have them all zipped in the roms folder (under mameplus etc.) Linked that folder as the source folder in MAME.
But still only about 10 of these roms are recognised in MAME, the rest are nowhere to be seen. Granted, some are NEOGEO roms, but I have the NEOGEO bios file in the roms file also.
I've audited the roms that it's not recognising, but still no joy.