playlists on iPad only play a handful of songs

I have an iPad 2. I only keep about 500 songs on it and all the songs are in playlists. It doesn't matter which playlist I choose, it seems each playlist only plays about 10% of the songs. I've tried removing the playlists from the iPad and resetting the play counts in iTunes to zero and then adding the playlists back to the iPad; it hasn't worked. When I click through each song on the playlist, they all play fine but it just seems the shuffle function will not shuffle all songs in the playlist. I suspect it has something to do with the play count only because it seems to be the same songs over and over. Any advice would be helpful. Thank you in advance.