Co znamenaju tieto errori

Prosim vas aka pricina moze byt ze mi vypise titeto errori:

Warning: require_once() [function.require-once]: Unable to access ../maincore.php in /NODE1/mgamecs.com/test/administration/who_is_online.php on line 2

Warning: require_once(../maincore.php) [function.require-once]: failed to open stream: No such file or directory in /NODE1/mgamecs.com/test/administration/who_is_online.php on line 2

Fatal error: require_once() [function.require]: Failed opening required '../maincore.php' (include_path='.:/usr/share/php:/usr/share/pear') in /NODE1/mgamecs.com/test/administration/who_is_online.php on line 2


a na tom 2 riadku sa nachadza toto:
require_once "../maincore.php";