Did you remap in side mame?
Start a game, tab, "Input (general)", enter, "player 1", "dial inc", enter, button you want mapped, (wait until mame excepts it), repeat for "dial dec" and then repeat for player 2 (if needed).
If you're trying to map to "dial analog", it isn't working because mame is expecting an analog input and a button is digital (IOW, how would mame know which direction to turn when button is pressed?).
If you're looking in mame32's settings, that's not where you remap individual keys.