Add Child to Widget not working

Hey everybody,
I’ve done a Playerlist and created some codings in my GameState with connection to my Playerlist Widget as you can see below.

I’ve already kinda done this before with adding widgets to a scrollbox for each found session and that just worked fine.
But whatever I do, when the Level is opening with the Gamestate it’s not doing anything and leaves the Playerlist blank.

You can see what I was trying to do in that picture, so if anybody has got a clue feel free to tell me.

I appreciate every help I can get!