I want to use the mute option on my Aguilar AG500SC amp more easily, and to do that I bought a latch pedal, the Boss FS-5L. What it does is switch on and of the Operate-light, but as soon as I plug the pedal into the footswitch input with a guitar cable, I lose my sound. None whatsoever, not with the pedal on, not with the pedal off. I've tried pushing the Operate/Mute button on the amp itself, but no improvement there. Any help?