need help on an AUDI A6 help!!!!!!!!

i am tryin to install a panasonic in dash screen i bought the wiring harness and connected evrything and the screen turns on but no sound, its a 98 audi a6 quattro with the bose system, on the harness is just like any other harness but for all the speakers instead of having two cables( the positive and the negative) it has two positives and one negative for each speaker, and also it has two grounds, i know it probably has an internal amp but how do i do it to get sound from the speakers? HELP!!!!!!!!!!!