How to tell when a unit has left the screen?

I am currently making a top-down shooting type map, using the keyboard for controls. All players have their screen centered on the same point, and my fire, which creates a unit and orders it to move straight up. Now, I want the bullet units to disappear when they leave the screen. I tried using the "Unit Leaves Region - Current Camera Bounds" but it didn't work.

I also tried using a region centered on the "camera" unit, which all player cameras are centered on, and testing when the bullet units leave that region. It works, but for some reason the region I use for testing doesn't center on the camera unit, despite me having a periodic trigger to re-center the region over the unit.

Is there any other solution I can use, or do you think I screwed up my triggers somehow? As in, why doesn't the region move? Is that trigger broken?

The easiest thing i can think of is to put a region at the side of the map and make it to that when a unit enters that region it is hide and then you can make it explode or die so it isnt there anymore.

That might not be the best way to go about it but im fairly certain it would work.

By the way, "leaves current camera bounds" means those blue lines around the edge of the map, right before the black boundary edge.

Hrm, looks like this post was hyper-informative!

That won't work very well. The player may only have so many shots, and the edge of the map could be quite some distance away. I could do it mathematically (find out how many "y" units it is from the center of the screen to the top plus some more), but I would prefer it work with "Unit Leaves Region"

[edit] Oh well, I just switched to hit-scan targeting. That cuts a lot of my triggers out.