Custom Event Wont Run

Hi guys so i’m trying run a custom event I made which currently just changes the material of an object. For some reason its not working.
Im keeping it quite simple but im not sure where the problem is.
Ive created a reference variable for the temple door (this is the object blueprint that contains the custom event).
Id really appreciate some help here ive spent hours looking around but ive not been able to find any solutions.