LDAP无法添加值

Question

我正在尝试为属性添加值。但它失败了，没有显示错误。这是我的代码：

function set_attribute($attribute, $uid, $service)
{
    $entries = $this->get_account($uid);
    if ($entries != false && count($entries) == 1) {
        $entry = $entries[0];
        $result = $entry->add(array($attribute => $service));
        $changedEntry = Net_LDAP_Entry::createFresh($entry->dn(), $entry->getValues());

        if (PEAR::isError($result))
            return false;
        else {
            $ldap = $this->conn;
            $ldap->delete($entry);
            $ldap->add($changedEntry);
            var_dump($entry->getValue($attribute)); // this result have new service
            $entry = $ldap->getEntry($changedEntry->dn());
            var_dump($entry->getValue($attribute)); // this result doesn't have new service
            $result = $entry->update();
            var_dump($result->getMessage()); // this results nothing
            if (PEAR::isError($result))
                return false;
        }
        return true;
    } else
        return false;
}

此函数返回true，不显示错误消息。