I am having troubles with require_once() in my application.

So, I have two folders: 'lib' and 'content'. Both are at the same level in the folder structure (i.e. 'Application' > 'lib' & 'Application' > 'content').

Under the 'lib' folder, I have a couple others:
  • lib > models
  • lib > views
  • lib > variables


Under my 'content' folder, I have the pages that are displayed in the browser (add.php, view.php).

On add.php, I have require_once('../lib/views/addClass.php');. When I run add.php in the browser, I get:

Warning: require_once(./variables/variables.php) [function.require-once]: failed to open stream: No such file or directory in C:\xampp\htdocs\application\lib\models\addClass.php on line 2


I can't figure out why it can't open the file. Any thoughts?

I am running XAMPP on Windows 7.