Hello forum, I am a big noob (just starting today :D) at UE4 getting started with Blueprints.
I was using the Starter Map to tinker with some lights. My particular goal was to create a couple of lights which can be toggled on and off by pressing a key, but only if a nearby general light switch (that you can also toggle on and off) is toggled on.
I created the general light switch in the level blueprint, and the two lights are implemented via a class blueprint.
In order to know if I can turn those two lights on and off, my class blueprint needs to know if the general switch is on or off, so I created a variable (in the class blueprint) of object type to reference the level blueprint and be able to get a boolean variable from there. The thing is, when I add the variable which references the level blueprint, I cannot save until I delete it because I get the following error message:

And when I press OK…

I have tried looking for a solution everywhere I could think of, but I have found none thus far. I apologize for asking if this is somehow an easily solved issue.