Compiz viweport switcher: I can't move up or down, only left or right

Sorryyy! I found the answer! Happy again!

I'm running Ubu 18.04. I always install compiz and wobbly windows, I just love them!

I've installed compiz many times. On my laptop usually set compiz to 16 desktops. I switch left or right, up or down with ctrl alt and the arrow buttons.

Now I have installed Ubuntu on my office comuter. It has a big monitor, so I set desktops to 5 by 4 = 20

Although I have 20 desktops set, after starting Mate, I only have 4 desktops, no matter what I set.

I can switch left or right.

I cannot, for the life of me, discover how to enable up and down desktop switching! (I can't remember how I enabled this on my laptop)

Will some kind soul please help me?