Check the Incompatible Devices list and make sure your Mp3 player isn't on there, or you could check the Compatible Devices list to see if your is on there.
I have a Sansa Clip MP3 player. I've downloaded several audiobooks from my local library. I've synched them to the MP3 with Windows Media Player. They show up in the player's index and the timer shows they are playing, but I get no sound from the player. The download to my PC was good because I can hear the books on the computer.
Does anyone have any thoughts? Thanks in advance.