Help USB Sync w/ Mac Issue


Very new to Android, so still trying to figure everything out. I'm having issues syncing my DX with my Macbook Pro. The first time I did it, it worked fine and I transferred all of my music over. Now when I try and do it, it goes right into "Charge Only" mode and the USB symbol does not even show up in the notification bar, so I cannot transfer files or anything.

Anyone else having this issue or know of a fix for it?