Keynote won't export movie with AUDIO

I've been using Keynote to record class lectures for years. I export them as movies, and post them on the Internet for my students. I've been doing that this semester, as recently as last week, but this week it doesn't work. Keynote records my lecture, including my voice, but when I export it the sound is not included. I spent 2 hours online with Apple in the past two days trying to find a fix, with no luck. The result is I have no way to post my lectures for the rest of the semester. Has anyone experienced this and found a work-around?