I just got an FM transmitter for my car and when I connect my iPhone 4 to it the cell signal drops all the way down to searching and then no service. The transmitter I got said it was for iPhone where you can use your phone through your car speakers. Am I missing some settings or something because I've tried a different type of transmitter with the same results. I've also tried my wife's 3g and it does the same thing. Any help or suggestions will be appreciated.