Forward declaration of class doesn't work compiler error!

Development Programming & Scripting
1

I am Learning UE4 with a Toturial, The instructor Types:

#include "CoreMinimal.h"
#include "PawnBase.h"
#include "TurretPawn.generated.h"

class ATankPawn;

UCLASS()

in.h class and types:

PlayerPawn = Cast<ATankPawn>(UGameplayStatics::GetPlayerPawn(this, 0));

in .cpp class BeginPlay Section and includes:

#include "Kismet/GameplayStatics.h"

I type EXACTLY as tutor but compiler says

“Pointer to incomplete class type is not allowed”

And I have to #include the class to make it work! How is it possible? I’m saying this again I type EXACTLY what he types!

2

Sorry i forgot to Also include this in the Q:
there is this code in .h Class:

private:
    ATankPawn* PlayerPawn;
3

NVM, He did that in the Next 2 Lessons so it was Bad Video Editing Prob