You do not hear sound out of your mp3 player? Maybe try turning the volume up on the mp3 player? Otherwise check to make sure both ends of the plug are tight. Other then that I am out of idea's. Maybe your dealer (truck, not drug) can check it out for you.I can not get my aux speaker to work , pluged in cassette ,is working, but nothing through speakers, any thing Im doing wrong.
Just to add to the confusion, I thought he was trying to plug some extra speakers into the stereo!LOL, I thought the same things the first time I read it also, had to slow down and read it again.