BMW 328i 1997. The radio is very erratic it works fine then when at times when i start car there will be no sound from the radio . The cassette works and the radio you can see the stations but there is no sound (volume) but there is sound when playing the cassette? Also the red light blinks as usual but when I try to activate the code by touching all the buttons so i could re enter the code nothing happens no enter code mode comes on. After a day or so the radio will start working fine. Its really odd any ideas??