ONLY ONE SUB IS WORKING

Question

I HAVE TWO 12" DUB MAGS HOOKED UP TO A 600W AMERICAN LEGACY AMP. ONLY THE RIGHT SUB WORKS. I HAVE CHECKED ALL THE WIRES AND TAKEN THE SUB OUT OF THE BOX TO MAKE SURE THE WIRES WERE STILL CONNECTED. I HAVE CHANGED THE WIRES FROM THE BOX TO THE AMP AND STILL NOTHING.