Do DEC Y instead of Y - 1. Do INC Y instead of Y + 1. The BUTTON command is also being used wrong. The parameter that goes in BUTTON(<this parameter>) is not telling the button for which it should respond. It should tell what type of press to respond to. IF BUTTON(2) AND #A THEN #A is a constant that represents the button A. Likewise, #LEFT is the left dpad, #B is the B button, etc.