playlist 'recently added' won't sync to iPod?

I have my settings so my iPod will only sync to checked songs, because I have more songs than will fit on my iPod. everything syncs except for the playlist 'recently added'. When it is connected to my Mac, in iTunes when I click the drop-down for the iPod and view the playlists, it is displayed as if the sync was successful and that my recently added songs are in the playlist, but when i look at my Ipod there is nothing in the playlist.