if not logged in - return to index

[eluser]miauksius[/eluser]
Hi,

I have a problem. I'm creating a guestbook, and I dont want that not logged in users could read the comments in it, so i tried this:

Code:

<?php

class Guestbook extends Controller {
    parent :: Controller ( );
    if ( $this -> session -> userdata ( 'logged_in' ) != TRUE )
    {
        redirect ( 'index.php/home' );
    }
}
?>

But it doesent work. It doesent redirect at all. Why? Could you give me some tips? Cause im gonna need this in other pages too.

Thank you for your help