Buggy audio on triggers

Hi,

I have this annoying problem and have come across this in several of my developments.  Sometimes the audio completely fails to play on a trigger.  I'm building an artefact where when the user clicks on an object it plays a feedback sound (when the timeline starts) on the feedback layer if the answer is correct or incorrect.  Now the incorrect audio plays just fine, but for some reason the correct does not. Sometimes it is the reverse.  And it is only on some slides not all slides.  I've tried to import the audio track on those slides, but it does not always work.  What am I doing wrong?