I have a presentation that spans 30 slides. I want one track of music to span the 1st 5 slides, another song to span the next 6 slides, different music to span the next 3 slides and so on. I have timed the music so that it is in sync with the affected slides but the music stops after the 1st slide of each group advances. How can I get the music to start and stop on the correct slides?