问PHP事务rollBack不工作

EN

$host   = 'localhost';
$user   = 'root';
$pass   = '';
$error  = '';
$dbname = 'tameras_finance';
// Set DSN
$dsn = 'mysql:host=' . $host . '; dbname=' . $dbname;
// Set options
$options = array(
    PDO::ATTR_PERSISTENT => true,
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
// Create a new PDO instanace
try {
    $dbh = new PDO($dsn, $user, $pass);
    $dbh->exec("set names utf8");
}
//Catch any errors
catch (PDOException $e) {
    echo $error = $e->getMessage();
}  

try{
    $dbh->beginTransaction();
    $dbh->query('SET @newDebit = (SELECT max(`debtor_id`) + 1 AS maxDebit FROM `vocher`)');
    for($x = 0; $x < count($debits); $x++){
        $dbh->query('UPDATE `vocher` SET `debtor_id` = @newDebit, `status_id` = "4" WHERE `id` = '.$debits[$x]);
    }

    for($x = 0; $x < count($others); $x++){
        $columns = '`acc_id`, `value`, `date`, `desc`, `reject`, `vo_type_id`, `user`, `debtor_id`';
        $vals  = "'".$accs[$x]."','".$values[$x]."','".$dates[$x]."','".$descs[$x]."','1','1','".$user."', @newDebit";
        if($others[$x] == 'e'){
            $columns .= ', `cheque_no`, `available_date`, `issue_date`, `bank_id`';
            $vals  .= ", '".$sns[$x]."', '".$availdates[$x]."', '".$issueDates[$x]."', '".$banks[$x]."'";
        }
        $dbh->query("INSERT INTO creditor (".$columns.") VALUES (".$vals.")");
        if($lists[$x] != 'e'){
            $lastId = $dbh->lastInsertId();
            $q  = 'INSERT INTO `creditor_cc` (`creditor`, `cc`) VALUES ';
            for($y = 0; $y < count($lists[$x]); $y++){
                $dif = count($lists[$x]) - $y;
                $q .= '(';
                $q .= '"' . $lastId . '",';
                $q .= '"'.$lists[$x][$y].'"';
                $q .= ')';
                if($dif > 1){
                    $q .= ',';
                }
            }
            $dbh->query($q);
        }
    }
    $dbh->commit();
} catch(PDOException $e) {
    echo $error = $e->getMessage();
    $dbh->rollBack();
}