Empty Genius Mixes App on iPod Nano (6th Gen)

The Genius Mixes App on my iPod Nano (6th Gen) is completely blank - it just tells me to switch on the Genius function on iTunes. I've done this already, and updated Genius on my Music Library before I uploaded any songs to my iPod; I can set the Genius Mix for the currently playing song, just the App is empty. Is it because I've chosen to manually add my music from the library to my iPod?

Thanks for the help in advance!