The reason is (after a long search):
Audi has probably changed in the range from 2000 to 2004 in 2002 b6 wiring.
ie all Audi built before the end of 2001 will need well this plug.
Since my car was built in 2002 I need another plug with Can Bus Adapter.
Since these operating the rear speakers, the mini subwoofer in the trunk and the automatic shutdown of the radio allows.
Too bad that this important information is not filed with the description of the item.
