Can't place system folder above root on Mac?

[eluser]Deadly[/eluser]
My folder structure is:

Code:

/Users/me/Sites/mysite
--- /application
--- /system
--- /web_root

index.php is in web_root with this specified for $system_path:

Code:

/Users/me/Sites/mysite/system

No matter what though, I keep getting this error:

Code:

Your system folder path does not appear to be set correctly. Please open the following file and correct this: index.php

Can't find a way to fix this at all! Help?