Auth::实例在用户登录时返回false

我正在创建一个新用户，然后尝试让他们登录，该用户被保存在数据库中，他们的角色也被保存。虽然我从来没有点击重定向说他们已经登录。我已经调试了Auth:：Instance->login，我得到了FALSE

public function action_index()
{
    $view = View::factory('index/home');
    if( Request::current()->post() ):
        $post = $_POST;
        try {
            $user = ORM::factory('User');
            $user->username = $post['username'];
            $user->password = $post["password"];
            $user->email = $post["email"];
            $user->logins = +1;
            $user->save();

            if ($user->saved() ):
                $user->add('roles', ORM::factory('Role')->where('name', '=', 'login')->find());

                $logged_in = Auth::instance()->login($post['username'], $post['password']); 
                echo Debug::vars($logged_in); exit;                 
                if ($logged_in):
                    HTTP::redirect("/dashboard/");  
                endif;
            endif;  
        } catch (Exception $e) {
            echo Debug::vars($e); exit;
        }
    endif;
    $index_page = $view->render();  
    $this->response->body($index_page);         
}

配置

return array(
'driver'       => 'ORM',
'hash_method'  => 'sha256',
'hash_key'     => 'bernardo',
'lifetime'     => 1209600,
'session_type' => Session::$default,
'session_key'  => 'auth_user',

)；

可能是哈希时密码出了问题吗？