Form Validation question

[eluser]macleodjb[/eluser]
I was running through the user manual on form validation and i was trying to have a rule use my own query as well as perform a check for required.

Code:

$rules['dname'] = "required|callback_check_displayname($email)";

I entered a name that i knew would error the call back so i could check my error message, and instead it did not error, and proceeded. So i guess my question is this the proper way to do this?

Secondly, how do you get two uri fields behind the url like codeigniter does. (see below)

like this www.ellislab.com/forums/viewforum/{forum id}

Do i need to create a sub folder under "controllers" called "forums" and then place a controller within this folder called "viewforum"?

I have my function added via a model in my controller, does my function need to live inside my controller?