2 or 3 gen shuffle - required disc cannot be found

Connecting both my shuffles to itunes. Everything appears normal. Both shuffles are recognized in Devices. I can see all the songs on them. When I go to put different songs on the ipod I get a message it cannot be synced because the required disc cannot be found. I have the latest itunes and I have restored both shuffles to factory settings and still getting that message. It will sometimes allow me to put one or two songs in and then the cannot find disc message pops up. Completely lost on this one. My other devices, classic ipod and ipad2 are working fine.