BindWidget variable is null (source code, debug)

Development Programming & Scripting C++
, ,
6 
//MyController.h
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Widgets | Inventory")
TSubclassOf<UUserWidget> WItemwidget;

//NewInventoryGrid.cpp
void UNewInventoryGrid::RefreshInventory()
{
//...
	UNewItemwidget* testwidget = ConstructWidget<UNewItemwidget>(MainCon->WItemwidget);

	if (testwidget != nullptr)
	{
		testwidget->Tilesize = TileSize;
		testwidget->ItemObj = ele.Key;
	}
//...
}

I put that code in NewInventoryGrid.h but still the variable null.

did i do it right?