Hello, I have received this interface (UNIVERSAL STALK ADAPTER 29-00 e11 022337 16/07 v1.62) with JVC 29-004 adaptor, but it does not work correctly. When connecting the interface the volume of cd-receiver lowers single to the minimum, and the controls of the steering wheel do not work. The connections I believe that itīs ok. Can you help me? My car is a Opel Astra G 99 and the cd-receiver is a JVC KD-BT1. Thanks, and sorry for my bad english.I donīt really sure if is necessary connect the blue wire to a negative part of the car.