Set Actor location not working need some help.

How do i do that exactly ? thx

And btw why is that the variable is emtpy/not valid? should i not try to fix that somehow then this must be the most basic logic to just get a reference to an actor then call the location from it whitout using nodes that put more heavy calculations to save performance? What can cause that the variabale is not valid?

Edit
I just fixed it with get actor of class just like you say and then from it i could drag directly to get world location and to ai move to node. Thx for the help