I recently bought bluetooth fm transmitter and tried using it on my 2002 opel zafira which has vdo cdr 500 radio in it. I tried launching it several times but it didnt work. I can't find how to get manual frequency (it only has frequencies that are saved or automatically searches for nearby radios) and thefore i can't use my transmitter. any suggestions on how to get it? I tried those "button combinations" but none of them worked