GetRandomReachablePoint?

Hello, Im trying to create my own BTTask thats sets an blackboard vector key to a random point in the nav mesh.
(Like the blueprint node to obtain a random point)

I did succesfully created an blueprint based task wich uses the GetRandomReachablePoint, But when im trying to do the same in c++ I always ending up in an editor crash as soon as I hit the play button.

Could some one point me to the right direction how to do this in c++, Or I just might over see a very simple thing. But yea I have no clue at the point.

EBTNodeResult::Type UTask_GetRandomLocation::ExecuteTask(UBehaviorTreeComponent & OwnerComp, uint8 * NodeMemory)
{
	AAIController* AIController = OwnerComp.GetAIOwner();
	APawn* ControlledPawn = OwnerComp.GetAIOwner()->GetPawn();
	UBlackboardComponent* BlackboardComp = OwnerComp.GetBlackboardComponent();
	FVector PawnLocation = ControlledPawn->GetActorLocation();

	UNavigationSystem NavigationSystem;
	FNavLocation NavLoc;

	if (NavigationSystem.GetRandomReachablePointInRadius(PawnLocation, Radius, NavLoc))
	{
		FVector NewLocation = NavLoc;
		BlackboardComp->SetValueAsVector(Key_RandomLocation.SelectedKeyName, NewLocation);
		return EBTNodeResult::Succeeded;
	}
	else
	{
		BlackboardComp->ClearValue(Key_RandomLocation.SelectedKeyName);
		return EBTNodeResult::Failed;
	}
}

Normally UE4 tells you which line the crash occurred in. Can’t you tell?
You get and use multiple points but check for none of them if they are nullptr or not.