How come Itunes isn't letting me download pre-purchased songs (that are now released) onto my ipod? HELP!

Hi! I recently pre ordered thte catching fire soundtrack. Now that it is oficially out, I would think that i ould just download the songs onto my ipod. But that is not thwe case. It is only letting me download 3 specific songs, but not the others. It took my money, and states that i purchased the songs! Please Help!😟