UgamePlayStatics (name followed by '::' must be a class or namespace name)

Hi I am trying to make an AI enemy. I am using this tutorial Unreal Engine C++ Tutorial - Stealth Game AI - YouTube and I am running UE 4.21.1 and Visual Studio Community 2017 version 15.9.4. In my AIPatrolController.cpp file is compiler giving me an error that name followed by ‘::’ must be a class or namespace name. I tried to include “Kismet/GameplayStatics.h” but it didn’t help.

#include "AIPatrolController.h"
#include "AIPatrol.h"
#include "AIPatrolPoint.h"
#include "BehaviorTree/BlackboardComponent.h"
#include "BehaviorTree/BehaviorTreeComponent.h"
#include "BehaviorTree/BehaviorTree.h"
#include "Kismet/GameplayStatics.h"

void AAIPatrolController::Possess(APawn * Pawn)
{
	Super::Possess(Pawn);
	
	/*Get reference to the character*/
	AAIPatrol* AICharacter = Cast<AAIPatrol>(Pawn);

	if (AICharacter)
	{

		if (AICharacter->BehaviorTree->BlackboardAsset)
		{
			BlackboardComp->InitializeBlackboard(*(AICharacter->BehaviorTree->BlackboardAsset));
		}

		/*Populate patrol point array*/
		UGamePlayStatics::GetAllActorsOfClass((), AAIPatrolPoint::StaticClass(), PatrolPoints);
	
		BehaviorComp->StartTree(*AICharacter->BehaviorTree);
	}
}

It’s UGameplayStatics not UGamePlayStatics, in C++ names of all entries are case sensitive.

Yes It worked. It was stupid mistake.