Accessing functions from other blueprints.

Hello. I’m having trouble accessing functions between blueprints. I created a function in the global postprocess blueprint that changes the scale of the depth of field. The problem is I can’t figure out a way to be able to run the function in my custom weapon blueprint. I tried dragging and dropping the function between graphs but when I run the game it crashes with a “failed to find function” error. Anyone know how to do this? Thanks!