More than likely a bad USB cable. This has been the case for me 90% of the time when it came to this error and I was testing various iPods and usb cables.
2nd possibility - bad dock port on the iPod itself OR bad usb port (try another?)
Some 3rd party iPod usb cables are terribly poor quality and some don't work at all. I don't normally recommend the most expensive parts for a lot of things with good reasoning, but this is an exception for sure - I highly recommend the apple-brand iPod USB cable as they have definitely had the lowest failure rate. They also have the fastest detection times with iTunes as well!
Try a different iPod USB Cable, preferably a pretty new one. No matter what brand the cable is, some definitely go bad over time or from damage such as moisture.
Был ли этот ответ полезен?