No audio sound

Photopia Creator:  I have made 10 slideshows. All 10 used to be fine, but I looked at all of them today and the Audio is completely missing on 2 of them. I can see the audio track at the bottom but it is silent when I play the slideshow. I can see the music note emblem on the slides that I have recorded a "voice over" but that is also silent when I play the slideshow. I can press on Slidetrack and also Slidesound and listen to the music and also listen to my voice over.....however when I play the slideshow it is silent. I have read the instructions on audio in the guide but it doesn't address my issue. Please help, what do I need to do to get the sound back. As I said It used to work completely and I was very satisfied. Thank you.