Trigger order a building to cancel production?

I'm trying to create a trigger that would order a building to cancel whatever unit it is producing

"Stop" didn't work like I was hoping it would

Can this be done?

Event-Unit starts building
Action-Stop production of unit

Sorry, thats kinda blunt, but they would both be under units.

I have the first part, but "stop production of unit" or anything like it doesn't seem to exist

Are you using a custom editor?