Problem with iTunes recognizing 2 different iPod Nanos.

I have an original 2GB Nano Silver (2nd Gen), and recently acquired a new 16 GB Nano (6th Gen). After using iTunes to install Playlists on the new 16 GB Nano, and accepting the software update for the iPod, it now refuses to recognize my old Nano. ITunes version listed is 10.1. I tried a Reset Sync History. Automatic sync is turned off. No luck, still cannot see old Nano. "Help" is utterly useless.