Is your characterBP actually called “Character”? You’ll need to cast to the actual name of the characterBP that is using this animBP. So if your characterBP is named DudeBro420BlazeIt, you’d use a Cast to DudeBro420BlazeIt node.
If it really is just called “Character”, then:
Is your character or characters that are actually using this animBP in the world?
If so, do you have the AnimBP assigned to their skeletal mesh in the characterBP? If you’re not sure, go to your characterBP, click the skeletal mesh component, find the Animation section in the Details panel, set Animation Mode to Use Animation Blueprint, and set Anim Blueprint Generated Class to your animBP.
This problem should only arise if the animBP you are debugging has no actual in-world reference to cast to, or if you are casting to the wrong BP class.