GetRandomPointInNavigableRadius returns always 'false'

Development Programming & Scripting AI
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1

In my code of BehaviorTree task node, I used GetRandomPointInNavigableRadius() to get vector point where a npc move to.

below is some of my code.

EBTNodeResult::Type UBTTask_FindPatrolPos::ExecuteTask(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory)
{
EBTNodeResult::Type Result = Super::ExecuteTask(OwnerComp, NodeMemory);

ABLOG_S(Warning);

auto ControllingPawn = OwnerComp.GetAIOwner()->GetPawn();
if (nullptr == ControllingPawn)
{
	ABLOG_S(Warning);
	return EBTNodeResult::Failed;
}

UNavigationSystemV1* NavSystem = UNavigationSystemV1::GetNavigationSystem(ControllingPawn->GetWorld());
if (nullptr == NavSystem)
{
	ABLOG_S(Warning);
	return EBTNodeResult::Failed;
}

FVector StartPos = ControllingPawn->GetActorLocation();
FNavLocation NextPatrol;

**if (NavSystem->GetRandomPointInNavigableRadius(StartPos, 500.0f, NextPatrol))**
{	
	OwnerComp.GetBlackboardComponent()->SetValueAsVector(AABAIController::PatrolPosKey, NextPatrol.Location);
	return EBTNodeResult::Succeeded;
}

return EBTNodeResult::Failed;

}

On “if (NavSystem->GetRandomPointInNavigableRadius(StartPos, 500.0f, NextPatrol))”, it always returns false
and the PatrolPosKey’s value is set to invalid so that the npc does not move.

How can I make the PatrolPosKey’s value valid?