Storyline - trigger not firing at end of slide

I have a Storyline project with a slide that the user has to click two links on in order to proceed. So I’d like to hide the Next button until that happens.

• 
  I added two variables to track whether the user had clicked the links or not, added variable references to the slide, and when I publish and click the links, the variables change correctly.
• I have a trigger on the slide to display the next button when the timeline ends if the user has clicked both links (the Viewed variables both equal True.) I’ve tried this several ways, one with a plain white box covering the Next button, that should disappear at the end of the timeline. 
• This works OK if the timeline is still in progress.  However if the timeline has ended when the user clicks the second link (and both Viewed variables become True), then the trigger does not fire. 

There’s probably something I’m missing, but I’ve been pondering this issue for a few days now, trying different things, and nothing seems to help.  Any ideas on a solution?