Professor Won't Slide on Ice

I can't remember what level I'm on but it has boxes and barrels and I have to get a barrel down to the sand and then push it on to a blue button. I've looked at the solution and it shows the professor sliding across the ice after pushing boxes but when I do it, it doesn't happen. What am I doing wrong?

Thank you for any help.

Linda

Oh! I love this game, too.

I'd need to know the level to be able to try this one myself. One thing I have found is that the professor will only slide if he's moving in the right direction when he hits the ice. If he just drops on to the ice, e.g. by falling off a platform or box, he won't slide. He'll 'run' on the spot for a while, but he won't slide sideways.

I enjoy this game, too. It makes a change from M3s, HOGs, TMs...