Event is not called on Widget from Controller


I am currently trying to create a chat, which will be available inside Host Game Lobby and in the
in-game HUD.
Because I want to reuse this Chat System, I decided to have a separate widget for the Chat System which I place into the HUD Widget and in the Host Game Lobby Widget.

The problem is when I try to call an event inside the Chat System Widget which is inside the Host Game Lobby Widget, Widgetception. My problem is that I am not sure how to address that Chat System Widget?
I tried different methods such as Cast To, Blueprint Interface, nothing really worked.
Is there some sort of limitation I am not aware of?


Here are some screenshots: