I use PowerPoint for classroom training on road rules, yesterday I tried a combined laser pointer/slide changer I'd bought. It's pencil shaped, you point it directly at the receiver unit to "click" for slide changes, but for some reason I always pointed at the screen and clicked - and of course nothing would happen.
I told my class of 16-year-olds to let me know when I did it, so the rest of the session was punctuated by frequent choruses of "Other way Zipper!".

When I used the laser pointer a similar thing happened - I would point the red dot at my laptop screen instead of the projected image, again to a chorus of "Other way Zipper!".

Today's class in a different college was done using a "SmartBoard". My slide changer didn't work with it so I used my trusty telescoping pointing stick - but these boards are touch-sensitive and everytime I tapped the board to make a point, the slide changed.

Some old dogs have trouble learning new tricks I guess.

At least the let you.