help for codeigniter

[eluser]Unknown[/eluser]
I'm using php5, and I tell codeigniter that my root folder for code igniter is:

$config['base_url'] = "http://127.0.0.1/";

This is where index.php is.
however, when I visit my controller, php echoes
out that the controller class is not found. what
am I doing wrong?

[eluser]Unknown[/eluser]
I just realized what I did wrong, sorry!