ipod nano 6th gen not recognized in itunes

I recently purchased a used "AS IS" ipod nano 6th gen. The only problem with it is that it's not recognized by iTunes. I was fairly sure on purchasing it that solving this would be as simple as resetting it, or, at worst, figure it out by googling the problem. The method involving holding down the sleep/wake button and volume down for 8 seconds until the apple logo appears didn't help. Putting it in disk mode didn't help. I have a mac and I suspect the original owner of the ipod may have used windows, so I tried both of these things again with my dad's PC. I at least got some response--an error message saying the usb device couldn't be read or something of that sort (I can look up the exact message again tomorrow if it's relevant).

I don't think it's the USB plug or cord, because both of these work with my iphone and another ipod nano in the household. I don't think it's itunes either, for the same reason. I'm running Lion, fully up-to-date, on a Macbook Pro. ITunes is also fully up-to-date.

I wouldn't be devastated if I can't fix it, since it still charges and plays music (the previous owner's hip-hop/club type music works pretty well for workouts), and it's probably not worth it to me to pay Apple to repair it. But…if anyone has any suggestions for things I can try to get it totally working, I'd love to hear them! 🙂