i have a 2004 MCS with the H/K system. last night i tried installing a Pioneer AVIC-N1 with a friend who is an intaller. we got it to produce video, but no sound. i cannot figure it out. i have the proper wiring harness and i jave the proper connections made, but i cant get the unit to make any noise . if anyone else has had this problem please let me know how you fixed it, if there is any special H/K think i need to get. thank you.