Timing the ‘Next Page’ button

I have converted PPT slides with voice over.  I don’t want the next slide button to appear until close to the end of the audio.  I tried setting timing for that button to ‘Appear After’ and set the time close to the length of the audio playback.  I have it selected to display for Rest of Slide. One or two slides this worked for but not on the vast majority.  How can I accomplish my goal?  Do I need to […]