Need support with check box function!

[tosse12]

I am not sure if this is where I should put my request thread, so please move it if this is in wrong thread.

Okey, I am trying to do a "Term of use" before being able to create an account.
And I am having problem to make sure that the "box" is checked.
Here is the following code

		function _checkRules($rules) {
			if {XXXXXXXXXX } {
				return true;
			}
			else {
				$this->form_validation->set_message('_checkRules', 'You haven\'t accepted the rules!'
			}
		}

and yea the most importent part is missing there, but I am not really a pro in Php

Almost forgot, this is the input form for this function:

<INPUT TYPE="checkbox" NAME="rules" id="rules" value="true" />

Shall rep u if u are able to help me ofc (common sense)

EDIT:
okey, I found one way to fix this but, my page goes all white (an error in my code?) -- Btw I am using Modern Acc v0.2

		function _checkRules($rules) {
			if (isset($_POST['rules'])) {
				return true;
			}
			else {
				$this->form_validation->set_message('_checkRules', 'You haven\'t accepted the rules!'
			}
		}

I also wonder if this is correct (I think only stain or/and Paxton can answer this? )

				$this->form_validation->set_rules('rules', 'Rules', 'required|callback__checkRules');