This can happen sometimes when the iTrip or RoadTrip has trouble communicating with your iOS device. This can usually be fixed with a soft reset on the device while the FM transmitter is plugged in. To perform a soft reset, press and hold the lock button (located on the upper right of your device) and the Home button (at the bottom center of your device) at the same time. Ignore the “Slide to Power Off” prompt, and keep holding the buttons until you see the iOS device turns itself off, then on, and the Apple logo appears. Then, let go of the buttons, wait for the device to boot back up, and try it again.
If you have a 3rd Generation iPod, with four buttons above the touch wheel, then none of our current iTrip Auto models is compatible. That iPod model requires a FireWire charge, and all current iTrip Autos provide a USB charge.