Q: Everytime I try to connect my iPod to my iMac it would connect then disconnect and etc. Any help?

I have an iPod 5th generation. Both my iPod and iMac are up to date on everything. The wire is fine and also are the usb ports. Everytime I plug my iPod in the iMac it wouldn't be able to connect to iTunes and it would keep on connect and disconnecting. Anyone who experienced this got through the problem and tell me the solution?