Hello,
Instead of a reference, which need to be set with the specific actor in the level you want to interact with. (On event begin play for example), do a “get all actors” selecting your blueprint in “actor class”. If you have only one actor of this class, drag a “get” from it and drag your bool from it (don’t forget to check your bool) If you have more than one actor, you will need to use a tag to know which actor activate : https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/FindingActors/Blueprints/index.html