Well, I am guessing AI is a character or pawn, and not controller. But regardless, you need to get the reference from the actor and transmit is down to the widget.
This video will greatly help you understand how to do it and much more: Blueprint Communications
-Cast from actor to the widget (maybe it’s a 3dwiget, then use get user widget object) and just set it to the widget.
it doesnt work…
its a character and i want it to have his health displayed on top of him
Right, and I told you what you needed to do. Have you watched the video and understand references/bp communications?