CakePHP error for the connexion with ACL - php

Question

I'm trying to understand how Cakephp works. I built a connection system with a simple form (username and password). When I click on the submit button (with the correct username and password), I always receive the same flash message, "Your username or password was incorrect". I tried many things, but I don't know how to fix it .
If I'm logged, I want to be redirect on Google (it's the test i try) .
Look at my code :
login.ctp (View)
<?php
echo $this->Form->create('User',array('action'=>'login'));
echo $this->Form->inputs(array('legend'=>'Se connecter','username','password'));
echo $this->Form->end('Se connecter');
?>
UsersController
class UsersController extends AppController {
public function beforeFilter() {
parent::beforeFilter();
$this->Auth->allow();
}
public function login() {
if ($this->request->is('post')) {
if ($this->Auth->login()) {
$this->User->id = $this->Auth->user("id");
$this->redirect('http://www.google.fr');
} else {
$this->Session->setFlash('Your username or password was incorrect.');
}
}
}
}
User (Model)
<?php
App::uses('AppModel', 'Model', 'AuthComponent', 'Controller/Component');
class User extends AppModel {
public $actsAs = array('Acl' => array('type' => 'requester'));
public function parentNode() {
if (!$this->id && empty($this->data)) {
return null;
}
if (isset($this->data['User']['group_id'])) {
$groupId = $this->data['User']['group_id'];
} else {
$groupId = $this->field('group_id');
}
if (!$groupId) {
return null;
} else {
return array('Group' => array('id' => $groupId));
}
}
public function beforeSave($options = array()) {
$this->data['User']['password'] = AuthComponent::password($this->data['User']['password']);
return true;
}
public $belongsTo = array(
'Group' => array(
'className' => 'Group',
'foreignKey' => 'group_id',
'conditions' => '',
'fields' => '',
'order' => ''
)
);
}
?>
The password in my table user (sql) :
password char(40) latin1_swedish_ci