public function deactivate()
    {
        if (!$this->sieve) {
            return $this->_set_error(self::ERROR_INTERNAL);
        }

        $result = $this->sieve->setActive('');

        if (is_a($result, 'PEAR_Error')) {
            return $this->_set_error(self::ERROR_DEACTIVATE);
        }

        $this->active = null;

        return true;
    }