Help !! NO sound from my new Sony CD player !! Help

I got a 1997 E420 and today I install a new Sony CD player CDX-M800 with VW's harness. everything looks fine, so power is not the problem, the AM/FM radio is function normally, but when I switch to CD, NO Sound at all !! I go back to the store I got the CD player from, the guy give me a demo one to try it, Still NO sound !!, so the CD player is ok, but how come is NO sound ? I have a stock Bose system, and I only install the CD play, the rest of the system are still stock ! Any answer to this problem ? I double check the harness wiring. everything is fine ! HELP !!



