pages.setActiveControlSet(controlSetId) Help Please

Can someone please clarify how this works. I’m on Page 1 and if you press a button in Set 2 I want to change the set to move to 1. I’ve tried a number of things but keep getting an "attempt to call a nil value (method ‘setActiveControlSet’) error.

I’ve tried calling this directly: pages.setActiveControlSet(1)

I’ve tried setting a variable in case that is what you need to do:
page = pages.get(1)
page:setActiveControlSet(1)

Actually, if I press the control for a bit instead of quick press, the active set moves to 1 with this: page:setActiveControlSet(1) but then jumps right back to set 2 while I’m pressing. I’m calling this from a Momentary control that is part of set 2 as the last thing in the function. Does it see that I’m calling from set 2 and set it back? Then how can you set the active control. Do I see to set some on.function can call it there?

Would be nice if the manual had an explicit example but can someone please clarify this for me please. Thanks.