I have a Kenwood kdc-bt558u head unit connected to a Rockford fosgate punch 200 dsm 2 channel with a JL audio 10 inch sub. So my head unit has three A/V outputs on the back (front, rear, and sw) when I hook up the amp to the sw and front nothing comes out but if I hook it to the rear it works but I can't control the sub and amp though the settings in my head unit I have to go to the amp to control it ( and it's hard to get too) dose any body know what might be causing this I want to hook it up to the sw A/V where it supposed to go i do have a lower amp fuse then the amplifier calls for it calls for a 50 and I've got a 40 in it. Thanks