Simple "Is On Screen" never triggers

I have what I thought was a pretty straight forward blip of code that simply will not work, and for the life of me I can't figure out why.

As you can see, the Web will randomly spawn a Spider at it's center every 5-10 seconds. I only want 1 Spider on screen at a time, so I've added a condition that, if the timer goes off, AND Spider is not already on-screen, THEN spawn a Spider.

The code as pictured never spawns a Spider.

If I simply remove the "X is on-screen", the web correctly spawns a Spider every so many seconds.

I know for a fact there are no Spiders already on screen. Can anyone tell me WHY this won't work?

Are there any spiders at all? Perhaps there are no spiders that are not on screen either? Which would make the condition fail, and action not run.

So "on screen" specifically refers to being visible in the viewport..? That's where I was mistaken then, I was treating "not on screen" the same as not existing in the layout at all. Thanks for clearing that up.

I figured out another way around it that doesn't even need a timer, just using the wait command for a random # of seconds instead, and that's working as expected.

You can use the system compare two values, spider.count=0, as an alternative.

If you want to spawn a spider even if there are spiders off-screen, you can use this trick:

Web On Timer "Spawn"

.. Spider is on screen : (nothing in this event)

.. Else : Web Spawn Spider