Symfony2:登录操作教程错误->_login_check没有返回值

我在symfony网站上制作了登录操作教程：http://symfony.com/doc/current/cookbook/security/form_login_setup.html

当我在表单中登录时，我会收到以下错误：

The controller must return a response (null given). Did you forget to add a return statement somewhere in your controller? 

这是我的安全。yml

security:
    encoders:
        Symfony'Component'Security'Core'User'User: plaintext
    role_hierarchy:
        ROLE_USER:        ROLE_USER
        ROLE_ADMIN:       ROLE_USER
        ROLE_SUPER_ADMIN: [ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]
    providers:
        in_memory:
            memory:
                users:
                    user:  { password: userpass, roles: [ 'ROLE_USER' ] }
                    admin: { password: adminpass, roles: [ 'ROLE_ADMIN' ] }
    access_denied_url: no_access
    firewalls:
        dev:
            pattern:  ^/(_(profiler|wdt)|css|images|js)/
            security: false
        login:
            pattern:  ^/login
            security: false
        secured_area:
            pattern:    ^/
            anonymous: ~
            form_login:
                login_path: /login
                check_path: /login_check
                default_target_path: home
            logout:
                path:   /logout
                target: /login
    access_control:
        - { path: ^/login, roles: IS_AUTHENTICATED_ANONYMOUSLY, requires_channel: https }
        - { path: ^/, roles: ROLE_USER }

我的安全控制器：

class SecurityController extends Controller
{
    /**
     * @Route("/login", name="login_route")
     * @Template()
     */
    public function loginAction()
    {
        $authenticationUtils = $this->get('security.authentication_utils');
        // get the login error if there is one
        $error = $authenticationUtils->getLastAuthenticationError();
        // last username entered by the user
        $lastUsername = $authenticationUtils->getLastUsername();
        return $this->render(
            'TripAdminBundle:Main:login.html.twig',
            array(
                // last username entered by the user
                'last_username' => $lastUsername,
                'error'         => $error,
            )
        );
    }
    /**
     * @Route("/login_check", name="login_check")
     */
    public function loginCheckAction()
    {
        // this controller will not be executed,
        // as the route is handled by the Security system
    }
}

点击提交按钮后的重定向是login_check，但其中没有代码，因为symfony说：the route is handled by the Security system但我明白这个错误。有人能帮我做这个吗？