CakePHP 2.0 - Able to Register, but cannot login -

im cakephp newbie, apologies if question has been asked search not find. have problem code below. works when register new user, problem when im trying login , error "invalid username or password'); please help

public function login() {  if ($this->request->is('post')) {         if ((!empty($this->request->data['user']) && $this->auth->login())) {             $this->session->setflash(__('welcome, '. $this->auth->user('username')));             $this->redirect($this->auth->redirecturl());         } else {             $this->session->setflash(__('invalid username or password'));         }     }  } 

//******* login ctp************

<div class="users form"> <?php echo $this->session->flash('auth'); ?> <?php echo $this->form->create('user'); ?>  <fieldset>     <legend><?php echo __('please enter username , password'); ?></legend>     <?php echo $this->form->input('username');     echo $this->form->input('password'); ?> </fieldset> <?php echo $this->form->end(__('login')); ?> 

//*******************before save *************************

 public function beforesave($options = array()) {     // hash our password     if (isset($this->data[$this->alias]['password'])) {         $this->data[$this->alias]['password'] = authcomponent::password($this->data[$this->alias]['password']);     }      // if new password, hash     if (isset($this->data[$this->alias]['password_update']) && !empty($this->data[$this->alias]['password_update'])) {         $this->data[$this->alias]['password'] = authcomponent::password($this->data[$this->alias]['password_update']);     }      // fallback our parent     return parent::beforesave($options); }