how to change require_once path setting

[regi168]

According the following error msg,  It seems appears need  to change some path setting.

[05-Apr-2011 15:57:24] PHP Warning:  require_once(/home/httpd/vhosts/regi168.com/httpdocs/includes/Core/loader.php) [<a href='function.require-once'>function.require-once</a>]: failed to open stream: No such file or directory in /home/easytrip/public_html/index.php on line 36
[05-Apr-2011 15:57:24] PHP Fatal error:  require_once() [<a href='function.require'>function.require</a>]: Failed opening required '/home/httpd/vhosts/regi168.com/httpdocs/includes/Core/loader.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/easytrip/public_html/index.php on line 36

where can I change the path setting for  require_once(/home/httpd/vhosts/regi168.com/httpdocs/includes/Core/loader.php

Thanks~

[ks-net]

 in configuration.php

$mosConfig_absolute_path  parameter

fix also and

$mosConfig_cachepath

[regi168]

thanks for your big help