A domain, a couple sub-domain, & multiplte instances

[eluser]phusiondesign[/eluser]
Ok, I think I am making progress... but need some further help.

I am starting with a fresh server state and got CI up and running. I got www.mydomain.com working, and it works from system/application/one.

Now I am trying to get one.mydomain.com to work from the same directory. I created a directory at mydomain.com/one and put a CI index.php file at that location but I am getting the below error. Any help?

Code:

Warning: require_once(/home/content/p/h/u/phusiondesign/html/domain/system/codeigniter/CodeIgniter.php) [function.require-once]: failed to open stream: No such file or directory in /home/content/p/h/u/phusiondesign/html/domain/index.php on line 115

Fatal error: require_once() [function.require]: Failed opening required '/home/content/p/h/u/phusiondesign/html/domain/system/codeigniter/CodeIgniter.php' (include_path='.:/usr/local/php5/lib/php') in /home/content/p/h/u/phusiondesign/html/domain/index.php on line 115