how do i get my ipod nano to connect to my computer?

when i plug the cable into the usb on my computer the screen lights up on my computer but there are no icons showing that my ipod is connected to the computer and when i log into itunes my ipod doesnt show up as being connected to the site either. obviously something is working on the cable and the ipod because of the screen lighting up but i don't know if maybe the connection is broken or something, even thought the usb ports are in perfect condition.