XML Sitemap Generator can’t notify google and bing

WP_DEBUG is a constant which you can define in wp-config.php to disable hiding of PHP errors and notices.

Add define('WP_DEBUG', true); to your config file to enable it.

Just remember to never leave it on for long on a live blog.

Since all pings fail this is likely not an issue with specific sitemap service, but with ping process itself. I think it might be HTTP requests failing for some reason, but there is no way to tell definitively from information you provided so far.