« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« PHP Parse Error »
PHP error debug
  Error: file(http://www.naag.org/backpages/naag/environment/RSS): failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found  
  Error type/ Nr.: Warning - 2 
  File: /var/lib/apache/htdocs/www.naag.org/assets/snippets/newsparserx/newsparserx.inc.php 
  Line: 426 
  Line 426 source: $data = @file($this->URL) or die ("Could not open a feed called: " . $this->URL);  
Parser timing
  MySQL: 0.1499 s(3 Requests)
  PHP: 6.4696 s 
  Total: 6.6195 s