Got a 94 nissan pathfinder,pulled the original radio out, to put a after market radio in , bought the conversion adapters to plug the radio directly back in to the wiring harness of the nissan. Every thing fit perfect . Powers up but NO SOUND! Put a speaker on the wires coming out of the after makket radio and I have sound, but nothing going threw the nissan wires to the speakers in the truck... WHY?