Why can't I change the volume using my iPod?

The RoadTrip has to use the "line-out" port on the bottom of the iPod, and that volume can't be changed by the iPod. However, if the volume seems abnormally low, it could mean a communication problem between the iPod and the RoadTrip.

You can fix that by performing a "soft reset." With the iPod plugged into the RoadTrip and both devices turned on, hold down the Menu and Select buttons on the iPod until an apple appears in the screen. Then you can let go and wait for the iPod to restart. After it restarts, try playing a song and see if the volume improves.