Why when I try to bridge my subwoofers my amp won't play. I have a 1200 watt sony xplod and two 12s they are a thousand watts a piece

Does the load of the stereo turn on amp? Stereo gets its B+ power from Amp?

One thing I could say is you have your sub and amp mixed up... if you have a 1200 watt amp you want a sub more than 1200 watts.. if you have an amp bigger than your sub you can blow them