Why is my iPod skipping over new songs?

I just added two new songs to my iPod nano 6th generation (which I have enabled for disc use). And when I just tried to play them on my iPod, I clicked on them and it showed up for one second and did not play at all - just skipping to the next song. It only happens with the two new songs I just added. Every other song plays fine. The two new songs that will not play are .mp3 format and have cover art and everything. They are listed on my Ipod, but neither of their cover art shows when I click on it and neither will play. However, they play perfectly fine in iTunes and on Quicktime.

Help?