1999 911 Radio install help needed

[Joe1]

I am installing a pioneer navigation radio into a 1999 Porsche 911. the car came with the factory navigation pcm radio system and factory amplifier in front trunk but is not a bose. I am using adapter harness 70- 1787. the pioneer radio turns on but will not play audio is there something different with this setup then other cars. is there maybe a different turn on wire for the amplifer, I have tried another pioneer and still no audio. thanks for your help