"Variable is not in scope"

Its a blueprint which suppose to hide or show a decal when a unit is selected. My current BP does not work (explained below). If you know a more efficient/easier way to do it let me know.

Here is my setup:
I try to send a message to my character’s Blueprint
At this point the character should receive the message and trigger show or hide the decal on the character. However when hovering over the booleon it says “Variable is not in scope”.