My ipod 30gig classic will not connect to itunes or even be recognized on my computer? what do i do?

Just recently found my ipod classic and i was trying to connect it to my computer but the computer nor itunes recongnized it. when i use a wall charger the ipod will charge but when i connect the USB to the computer it will not charge or be recognized. what should i do or is there a problem with the charger port?