Requiring the global.php file

[artifice]

I have two identical files. One is inside my forums directory (/home/EXAMPLE/public_html/forum/) and the other is in a testing subdomain (/home/EXAMPLE/public_html/testing/). Both files change directories to the forums directory like:

chdir('/home/EXAMPLE/public_html/forum/')

And then:

require_once('./global.php')

The problem is that the file in the testing subdomain does not correctly receive the vBulletin information while the other file does. There are no errors in requiring, it just doesn't work. I think that for some reason when global.php tries to require it's own files the path is wrong. Whatever the problem is, how do I fix it? Thanks in advance.