Bradley's dashboard

Ok so heres the issue. I have a first gen iTouch and a Alpine in dash head unit. It was working fine connected through the usb connection on the front of the unit but now it shows an ERROR on the head unit when the iTouch is plugged in. My macbook pro recognizes the iTouch and you can still listen to the music via the head phone jack on the iTouch. I reset the entire iTouch back to factory settings and still it is not working on the head unit only showing ERROR on the head unit screen. Anyone with advice or idea as to why this would be happening please let me know and thank you.