Can't trigger Enemy AI Class BP from Level Blueprint

I want my Class Blueprint (Enemy AI) to launch once a certain event happens in the Level Blueprint. Most tutorials I could find required to add a reference to the class BP placed in the world. However, there are about 60 instances of this Class BP in the level, so I don’t want to activate each one separately, but instead make the general AI Class Blueprint react to said event in the level. I tried to make the Level BP change a boolean variable to true once the event is executed, but even after I finally managed to somehow get the variable into both blueprints it still doesn’t work…

This is the Level Blueprint while the event is triggered, but can’t get past the “Cast To” node

This is the Class Blueprint’s Event Graph. Works flawlessly when I take out the branch. For clarification: Gegner Blueprint is the pawn possessed by DetourGegnerAI, GegnerBT is its behavior tree.

Where is the mistake? I also tried to replace Event Begin Play with Event Tick in the class BP, but it didn’t help…

After having tried numerous solutions and watched/read tutorials and forums for at least 10 hours I’m pretty desperate at this point. I really hope someone can help me here as I’m a total noob in game making and have little to no programming experience :frowning: