Trouble with mapping Area 51 grenade button

[coldcoffeecup]

This question might be stupid, as I can't seem to find anything about it online, so maybe everybody else has figured it out. In any event...

I just setup 2 aimtrak guns in my arcade, and everything seems to work fine. There are 2 side buttons per gun (left/right), which I've mapped to player buttons 2/3 (trigger is mapped to button 1). For some reason this won't trigger throwing a grenade in Area 51 when they're available, and I can't for the life of me figure out how to map them correctly in MAME. In other games like Alien 3 the side button works to throw a grenade, so I assume I'm just mapping it wrong in MAME.

Any suggestions?! Thanks in advance!

[UEDan]

In the original Area51 game you would either shoot the grenade or press start to throw a grenade.

[Endprodukt]

Yeah, you have to shoot the grenade on the screen.