Error "Extra content at the end of the document"

Hi there !

I have a problem with this Plugin. When I try to go to I have this error :

This page contains the following errors:

error on line 2 at column 1: Extra content at the end of the document

Below is a rendering of the page up to the first error.

Then, if I read the source code :

<?xml version=”1.0″ encoding=”UTF-8″?>

<b>Fatal error</b>: Call to undefined function network_query_posts() in <b>/homepages/38/d153135156/htdocs/rhonalps/portail/wp-content/recent-global-posts-feed.php</b> on line <b>42</b>

Can you help me ?