I'm currently using a Fender Blues Junior. When my guitar is plugged directly into the amp, everything's fine. But with the pedals(e.g. Ibanez Ts-9/Cs-3 etc), the volume will start fluctuating. It'll be fine at first but after awhile, the volume will become softer, back to normal, softer again and sometimes, no sound at all. What's the problem? Please do help! Thanks!