,How to use component ref?

I’ am totally new at UE4 and I have propably stupid question.

I got two objects. One of them is child of second. Is it posible to use component object reference(Child Actor) similar to global variable (VariableToTakingThings)?

214089-q0.png

I were trying to cast it, but as you can see there is warning, which says that it would always fail (I’am sure that Child Actor class is correct). Of course I can use global variable as below, but I think that this isn’t straight way.