BP Widget Component - C++ class & interface casting

I can’t make it to work but I think I’m doing it wrong…

USelectableActor_HUD *widget2 = CreateWidget(this, hudWidgetClass);

USelectableActor_HUD = My C++ widget class.
hudWigetClass = the class of the BP widget derivated from USelectabeActor_HUD, obtained by a ConstructorHelpers.
I also tried with this->GetGameInstance() since the first parameter ask to be a GameInstance, but that doesn’t work anyway…