"on click" animations won't advance

I have a presentation with some non-animated slides and some animated slides.
Left clicking on the mouse will advance through the non-animated slides, but
has no effect on the animated slides. Using other methods (space bar, page
up/down, etc) will step through the animations and advance to the next slide,
but the mouse has absolutely no effect on the animated slides - either
stepping through the animations or advancing to the next slide.
Interestingly enough, when I remove the animations from any slide, that
particular slide will STILL not advance with a left-click to the next slide.
This is important to me because my presentation remote only has a left click
or a right click button, neither of which can be reprogrammed to a space-bar
or page key.