When it was an object, no 
When it was an actor reference, it’s the correct type, but it still needs assigning. It needs to point at the exact BP you want to talk to, the type is not enough.
For all the engine knows, you might have 500 BPOutage blueprints in the level, it needs to know which one.
If you are putting the BP that’s making the call in the level, then you can assign the reference by making it ‘instance editable’ ( click the eye next to the variable ) and using the eye dropper tool on the BP in the level.
Otherwise, you have to set it at runtime, like we did.
Do you get it?