Behavior Tree not work

hey i been trying learn behavior tree from this
now i have 1 problem that idk why happen .
so we have on see function like this::

SensingComponent->OnSeePawn.AddDynamic(this, &AAIpatrol::OnplayerCaught);
void AAIpatrol::OnplayerCaught(APawn * Pawn)
{

AAIContoller* PawnController = Cast<AAIContoller>(GetController());

if (PawnController)
{

	GEngine->AddOnScreenDebugMessage(-1, 3, FColor::White, TEXT("u been seen"));
	PawnController->SetPlayerCaught(Pawn);

}

and function setplayercaught()
void AAIContoller::SetPlayerCaught(APawn * Pawn)
{
if (BlackboardComponent)
{

	BlackboardComponent->SetValueAsObject("Target", Pawn);

}

}

now problem is when he see player and reach her(move to blackboardkey “target” ) behavior tree become inactive and dont restart to go back and do left task again which is simple task for see its go back like this
EBTNodeResult::Type UTask::ExecuteTask(UBehaviorTreeComponent & OwnerComp, uint8 * NodeMemory)
{

GEngine->AddOnScreenDebugMessage(-1, 3, FColor::White, TEXT("loop"));

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
}