Warning: require_once(phing/Task.php) [function.require-once]: failed to open stream: No such file or directory in /var/www/pyg/lib/symfony/vendor/phing/tasks/ext/XmlLintTask.php on line 2

Fatal error: require_once() [function.require]: Failed opening required 'phing/Task.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/pyg/lib/symfony/vendor/phing/tasks/ext/XmlLintTask.php on line 2