When you tested off layout was the switch button connected as well as the toggle?
I'm not actually sure how these machines work inside, but my first thought is that the input needs a 'de-bounce' circuit. This is simply a small capacitor and a very large(high resistance) resistor, that will smooth out any chatter on the button or switch when it is pressed.
Anyway, if the original button was connected in the test, it could have shared the debounce with your switch.
JGL
