Sound doesn't play?

Hey, so was in the process of making my next toon, when i realized the sound file i'd imported doesn't play as move frames on the timeline. It'll play if  I press play from the start of the timeline, but once stop it or try to move the position back or forth it just starts ignoring me all together. This has to be some kind of setting i've accidentally changed, but I can't seem to find what i've done? Anyone else have this problem?