[Alan Anderson]

What you posted has several While loops visible. None of them ever terminate. The big Case containing the Flat Sequence requires input from two of those loops. Since the loops never produce a value, the Case will never be able to run.

I suspect what you really want is to put the Case inside the loop where you're reading the analog input named POT, and to move the stuff from the Joystick-reading loop into that same loop as well.