private function toXPath($css_selector)
    {
        $xpath = Null;

        try
        {
            $xpath = $this->selector->toXPath($css_selector);
        }
        catch (\Exception $e)
        {
            $this->logger->logError('E003', array($css_selector));
            $this->logger->logError('E000', array($e->getMessage()));
        }

        return $xpath;
    }