Then you need two different images. Attached are two test images with the OFF and the ON state. Place the indicator over the words MUTE OFF with the code
"MASTERMUTE:b" and it will blink red and black as in OFF/ON.
On the Button "MUTE" have a command "MASTERMUTE" ahh what the hell, here is a test skin. Load it from your menu.skin with the command "MENU;TEST.skin"