Vbulletin Integration failed :(

[jacksony]

Hi,

I am trying to include the vbulletin system into wordpress page with the code:
<?php
include 'forums/index.php';
?>
(the forums folder is in the same level as wordpress wp-content)

But I got this error message:
<b>Warning</b>: require(./includes/class_bootstrap.php) [<a href='function.require'>function.require</a>]: failed to open stream: No such file or directory in <b>/var/www/vhosts/*******.com/httpdocs/forums/vb/bootstrap.php</b> on line <b>30</b><br />
<br />
<b>Fatal error</b>: require() [<a href='function.require'>function.require</a>]: Failed opening required './includes/class_bootstrap.php' (include_path='.:/usr/share/pear:/usr/share/php') in <b>/var/www/vhosts/*******.com/httpdocs/forums/vb/bootstrap.php</b> on line <b>30</b><br />

Can you advise what I can do to do the integration? Thanks!