The Physics Constraints Can not Break With c++

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My English not very well, i’ll try to describe clearly:
(1) I use C++ to initialize Componen like below: It works well.

phyConstCmp->SetWorldLocation(middlePos);
	FString meshCmpName = this->GetComponentByClass(UStaticMeshComponent::StaticClass())->GetName();
	FConstrainComponentPropName tmp;
	tmp.ComponentName = FName(*meshCmpName);
	if (!meshCmpName.IsEmpty())
	{
		phyConstCmp->ComponentName1 = tmp;
	}
	if (!targetActor)
	{
		return;
	}
	phyConstCmp->ConstraintActor2 = targetActor;

	phyConstCmp->SetLinearXLimit(LCM_Limited, 1.f);
	phyConstCmp->SetLinearYLimit(LCM_Limited, 1.f);
	phyConstCmp->SetLinearZLimit(LCM_Free, 0.f);
	phyConstCmp->SetAngularSwing2Limit(ACM_Limited, 45.f);
	phyConstCmp->SetAngularSwing1Limit(ACM_Locked, 0.f);
	phyConstCmp->SetAngularTwistLimit(ACM_Locked, 0.f);

	phyConstCmp->InitComponentConstraint();
	isInitPhyCmp = true;

(2) Then , I want to break the Constraints , i used like this. But it is not break, is there something that i did not do?

void AMyTest::BreakConstraint()
{
	phyConstCmp->BreakConstraint();
}

(3) I want to break or resume the Constraints by my control, so i use the code:, But it seem can not do work well ,What is the right method to build this use C++?,

void AMyTest::ResumeConstraint()
{
	phyConstCmp->UpdateConstraintFrames();
}

Thank you !