session auth become null when I change url manually

Hi!

I try to understand why, when I change the controller and the action manually in the url, the session auth object ($auth = $this->session->get('auth');) becomes null ?

Scenario :

I log into the app I'm redirect to /index/index (But, in the url bar, it keeps saying /session/index) I change back manually to /index/index And I'm redirect to /session/index again :(

Any reason why ?

This the code of my DI :

    $di->set('session', function() {

        $session = new \Phalcon\Session\Adapter\Files();
        $session->start();
        return $session;
    });

This the code of my login function :

    private function _registerSession(User $user) { 

        $role = new Role();

        foreach ($user->userrole as $ur) {

            /* @var $r Role */
            foreach ($ur->role as $r) {

                $role = $r;
            }
        }

        $this->session->set('auth', array(

            'UserID' => $user->UserID,
            'Name' => $user->Firstname . " " . $user->Lastname,
            'Role' => $role
        ));
    }

This is the code where the security is checked from the INVO application :

public function beforeDispatch(Event $event, Dispatcher $dispatcher) {

        $auth = $this->session->get('auth');

        if (!isset($auth)) {

            $role = 'Guests';
        } else {

            $role = $auth["Role"];
        }

        $controller = $dispatcher->getControllerName();
        $action = $dispatcher->getActionName();

        $acl = $this->getAcl();

        $allowed = $acl->isAllowed($role, $controller, $action);

        if ($allowed != Acl::ALLOW) {

            //$this->flash->error("You don't have access to this module");

            $dispatcher->forward(

                array(

                    'controller' => 'session',
                    'action' => 'index'
                )
            );

            return false;
        }
    }

Thank you for your feedback.

Daniel