你好，为什么多表关系模型回滚不了
// 测试 start
D()->startTrans();
$map=array();
$map['sch_bid']='777';
$map['att'][0]['sch_bid']='777';
$result=D('Child')->relation('att')->lock(true)->add($map);
$map2=array();
//$map2['sch_bid']='888';
//$map2['att'][0]['sch_bid']='888';
$result2=D('Child')->relation('att')->lock(true)->add($map2);

//dump($result);
//dump($result2);
//exit;

if($result && $result2){
echo "<script language=javascript>alert('事务成功');</script>";
D()->commit();//成功则提交
}else{
echo "<script language=javascript>alert('事务失败');</script>";
D()->rollback();//不成功，则回滚
}
// 测试 end