Songs that play in iTunes won't play on iPod

I have two songs, not from iTunes, that will play in iTunes and not on my iPod Nano. I have others just like them that do. I have tried troubleshooting the iPod and iTunes, everything short of a full uninstall and reinstall. I had to do a complete hard drive wipe and clean install. They played fine before that. I have done Disk Utility and nothing popped up.

I have the most recent version of iTunes and my iPod software is up to date. Running OS Mavericks, 10.9.2.