public function deleteEntry($dn)
    {
        if (! (@ldap_delete($this->connection, $dn))) {
            $code = @ldap_errno($this->connection);
            throw new PersistenceException(
                sprintf(
                    'Could not delete entry %s: Ldap Error Code=%s - %s',
                    $dn,
                    $code,
                    ldap_err2str($code)
                )
            );
        }
    }