Try setting the value of letter progress instead of adding to it so that 1st letter pressed = set letterprogress 1, 2nd letter pressed = set letterprogress 2 and only have the sequence run when letterprogress = 6. Then, to ensure you can't just press the final letter for letterprogress = 6, set up some conditions so that, for example, 2nd letter can only be pressed if letterprogress already = 1, 3rd letter can only be pressed if letterprogress already = 2. Remember to set letterprogress back to 0 when the sequence is initiated.