songs wont load

hi, ive recently dug out my dj control instinct thats been in its box for a couple of years, and after setting it all up on my macbook, everything is working fine on the decks. however when i try to load a song onto either a or b, its just not working at all. it lets me load sample sounds i.e snare & ride, however, no songs. i thought this was because ive used youtube to mp3 converter to get a few songs, however its not because its also not working on the free u2 album everyone got on itunes. someone please please point me in the right direction as i went on my mates dj kit and loved it, and really want to get this thing set up.

cheers in advance!