Grouper : XML parsing error

Grouper - Documentation

PHP's built-in XML parser reported an error to Grouper's XML plugin while attempting to parse the data.

The source data contains invalid XML: If the source data is an Atom or RSS feed, go to FeedValidator.org and enter the URL of the feed to check whether it is valid. If it is not valid, contact the publisher and let them know that their feed is invalid. Be sure to send them to the feed validator to help them figure out how to fix it.
The source data uses an encoding that PHP's XML parser doesn't support: The encoding is usually indicated in the first line of the raw source of the data (look for "charset"). If you have purchased CaRP Koi and CaRP Evolution, use the Transcode script which is bundled with them to transcode the feed to UTF-8 (usually--or ISO-8859-1 in rare cases).
The URL you gave to Grouper doesn't point to an XML file: Load the URL in your web browser and see whether what comes up is XML or not.