What kind of variable are you dealing with? What’s its type? It should be the type of your custom widget blueprint. This should be the variable that you set right after using the Create Widget node.
Otherwise, if that’s not the problem, have you checked to make sure your animation is public? If I recall correctly, it should be public by default, but it can’t hurt to look.
Assuming your animation is public, you should be able to find it from your widget’s pin if you look under Variables → Animations.
If you’re still having trouble, I’ll post a screenshot this evening when I next get a chance to fire up the engine.