There's nothing wrong with your panels. It's these two lines that are causing the problem:
ON_T = mapon();
ON_Y = mapoff();
This means ON_T = the value returned from mapon. This causes the program to fail, as when you press T, it tries to run a function that doesn't exist.
You need to change the lines to:
ON_T = mapon;
ON_Y = mapoff;
No parenthesis means ON_T = the function mapon.
EDIT: You also need to change your functions to what Old Dude suggested to make them turn your panel on off correctly.