Playing tmnt in time and something feels off, is this normal?

[MadMartigan]

I’m wondering if something is up with my buttons. I am playing turtles in time and when I press jump and attack at the same time my turtle jumps really high and does his kick move straight up. I can’t seem to pull off the attack and jump move at the same time. Was the special attack this hard or is my buttons messed up. Think it’s using an iPac4.

I can do the special attack with the turtles but not on command, it also usually ends up doing that jump move for some reason most of the time

Is there a way to check my buttons on another game that requires double pressing but not a beat ‘em up. I just purchased this machine and messed up my led Blinky so I was hoping this isn’t related

[MadMartigan]

I should had that it’s a mame rom, using an ultimarc ipac4, all buttons are correctly mapped.

[KenToad]

For me, it works when I'm also pressing left or right at the same time. The jump kick thing happens when I'm standing still.