use glpi as subdomain

hello guys,
Well, i'm using GLPI as subdomain (glpi.mydomain.com), but some links is broken, because i need to use "$CFG_GLPI['root_doc']" empty for the GLPI works like a subdomain, but i see what some parts of the code don't get the configuration automatically, one sample is the file commonglpi.class.php in the function "showNavigationHeader($options=array())", in the $target variable for example get the value with $_SERVER['PHP_SELF'], getting the document root of the application, and this ocurrency exists in the other parts of the project.

Has anyone ever experienced this? Or exists other solution?

Regards.