i was cleaning out my truck the other day and was sitting in the back of my crewcab (i have the R/F system) and noticed that the rear control panel has selections for: AM/FM, CD, DVD, AUX. when i hit the mode button, i could only select the radio or cd, but not the AUX. why is this? i looked in the manual and i seemed to indicate that this should happen. i understand that i cant select dvd, as i do not have one. but aux? would be nice to be able to do this for my rear passengers who want to listen to a mp3 player.