I can't seem to shoot when playing Carnevil

I'm using Mameuifx32 that I downloaded here and I can't seem to shoot when playing Carnevil. I have mouse input enabled and the shoot/reload buttons mapped to both mouse buttons. The mouse moves the crosshair perfectly and the reload button works, but when I press the shoot button it just makes the sound, but it doesn't actually shoot. What could I be doing wrong?

Never mind. I figured it out. I didn't realize I had to calibrate the gun first. I'm not the sharpest light bulb in the drawer if you catch my drift.