Tank Auth is_logged_in() problem

[eluser]Unknown[/eluser]
I have this problem, when user logs out, he can still go back to previous page using browsers go back button. For some reason, if it is index method then everything is working fine.

Any ideas how can I fix this problem?

Thanks!

Code:

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class Site extends CI_Controller
{
function __construct()
{
    parent::__construct();

    $this->load->helper('url');
    $this->load->library('tank_auth');
    $this->load->library('form_validation');
}

// Working fine
function index()
{
    if (!$this->tank_auth->is_logged_in()) {
       redirect('/login/');  
    } else {
       $this->load->view('welcome_message');
    }
}

// id_logged_in() not working if user use browsers go back button
function test()
{
    if (!$this->tank_auth->is_logged_in()) {
       redirect('/login/');  
    } else {
       $this->load->view('welcome_message');
    }
}
}

UPDATE!
I find this: http://www.robertmullaney.com/2011/08/13...deigniter/
Now all I need to do is just add $this->output->nocache(); to my constructor.

If there is better solution, please let me know.
Thanks!