Variables not working when set for "when media completes"

I'm having all kinds of problems with my variables.

Let me first layout what I'm trying to do, then what the problem seems to be:

-I have a number of slides where I basically have a paragraph, and I want the user to click on a number of words.  In some cases there are 11 words they need to click.  

- Each word has a hotspot over it so that the user can click the word.  Those hotspots trigger a rectangle to go from hidden to normal, which animates it in and circles the word.  It also Triggers a brief audio file to play, where I explain briefly what the word means.  

- Once the user has clicked on all of the words, and listened to my audio, I would like to automatically display a "conclusion" layer that should have one final bit of audio from me, summarizing the paragraph.  I don't want this to play unless all of the words have been clicked and all of the other audio has been listened to.  And I want this to display automatically.  And the user should be able to click on the words in any order they would like.

At first, I simply set it so that once the associated rectangles were all "normal" instead of "hidden" then the "conclusion" layer would show automatically.  But there were a few problems with this.  Namely:

- If the user clicks multiple words too quickly, the audio overlaps, and 

- whichever the last word was, you wouldn't hear the audio because it would go straight to the "conclusion" layer once all the rectangles are "normal" which happens the instant  you click on the associated hotspot, which didn't give enough time to play the audio that is also attached to that hotspot.

To remedy these problems, I decided to split up the audio onto different layers, and have each hotspot display the associated layer, which just had the audio set to play when the layer's timeline began.  

- Then, I set a number of True/False Variables that would all be set to "False" by default, but would be changed to "true" once the media on each layer completed.  

- On the base layer, I created a Trigger that said "Show Layer - Conclusion" when Variable changes - Variable - Variable 1" on the condition that "Variable 2 is equal to Variable Value: True", AND "Variable 3 is equal to Variable Value: True" AND "Variable 4 is equal to Variable Value: True" etc etc.  

Unfortunately this didn't work, even after all of the audio completed, the Conclusion layer didn't show.  I even tried changing to to change the Variables to True when the timeline ended on their layer instead of when the media completed, but that didn't work either.  However, if I change the variables to change to "true" when the media starts, then it works perfectly.  Why would that be?  Am I doing something wrong, or is the Variable behavior not working as it should when media completes?

This is a bit complicated, so there is lots of room for error.  I'm betting if I look hard enough I have one thing wrong and it's causing the whole thing to fail.  I wonder if there is a way of seeing which variables switched to true, and which ones were still false?