Rattling

Hey there,
Well I have a '99 Civic Coupe EX with the 6 spkr factory system. With that I have added an amplified 10" Bazooka Tube in my trunk. It is excellent for what I'm looking for in a sounds system. The only this is that the right-rear section of the back panel is starting to have a slight rattle to it. I've had someone put a finger on it and hold it down, while it's playing and it's definitely not a huge rattle. I was wondering how I'm to rid of that rattle. If anyone could help me out, I'd really appreciate it.