Hi,
Make sure you are using the same Apple ID on your computer as your are on the iPod nano.
And make sure iTunes is up to date.
Mac
- Open iTunes.
- From the menu bar at the top of your computer screen, choose iTunes > Check for Updates.
- Follow the prompts to install the latest version.
Windows
- Open iTunes.
- From the menu bar at the top of the iTunes window, choose Help > Check for Updates. Learn what to do if you can’t see the menu bar.
- Follow the prompts to install the latest version.