Service not triggered : The controller must return

Hi everyone and huge thanks for the help, I am trying to get FOSFacebook work, but it seems to be impossible until now. I tried a lot of configuration, and a lot of fix but nothing worked for me.

Here is my configuration :

security.yml

chain_provider:
    chain:
        providers: [fos_userbundle, fos_facebook_provider]
fos_userbundle:
    id: fos_user.user_provider.username
fos_facebook_provider:
      id: fos.facebook.custom_provider

firewalls:
    dev:
        pattern:  ^/(_(profiler|wdt)|css|images|js)/
        security: false
    main:
        pattern: ^/
        form_login:  
            login_path: fos_user_security_login
            check_path: fos_user_security_check
            provider: fos_userbundle
            csrf_provider: form.csrf_provider
        logout:       true
        anonymous:    true
    public:
          pattern:   ^/
          fos_facebook:
              app_url: "http://apps.facebook.com/myApp/"
              server_url: "http://www.mywebsite.com"
              login_path: /facebook/login
              check_path: /facebook/check
              default_target_path: /
              provider: fos_facebook_provider
          anonymous: false
          logout:
              handlers: ["fos_facebook.logout_handler"]

config.yml

fos.facebook.custom_provider:
    class: Bundles\UserBundle\Security\User\Provider\FacebookProvider
    arguments:
        facebook: "@fos_facebook.api"
        userManager: "@fos_user.user_manager"
        validator: "@validator"
        container: "@service_container"
fos_facebook:
    file:   %kernel.root_dir%/../vendor/facebook/php-sdk/src/base_facebook.php
    alias:  facebook
    app_id: myid
    secret: mysecret
    cookie: true
    permissions: [email]

routing.yml

    _security_check:
        pattern:  /facebook/check

    _security_logout:
        pattern:  /logout

Twig Template

<script type="text/javascript">
    function goLogIn(){
        window.location.href = "{{ path('_security_check') }}";
    }

    function onFbInit() {
        if (typeof(FB) != 'undefined' && FB != null ) {
            FB.Event.subscribe('auth.statusChange', function(response) {
                if (response.session || response.authResponse) {
                    setTimeout(goLogIn, 500);
                } else {
                    window.location.href = "{{ path('_security_logout') }}";
                }
            });
        }
    }
</script>
{{ facebook_initialize({'xfbml': true, 'fbAsyncInit': 'onFbInit();'}) }}

UserController.php

 * @Route("/facebook/check")
 */
 public function loginCheckFacebookAction(){

 }

And the provider and the modification to User class (as in the Readme).

But the problem is that the service not seemed to be called. Indeed, the method in the UserController must be a dummy method, and it is not like that here. The method is called and of course I get this error :

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

What is my error here ?

Remove your UserController route/action loginCheckFacebookAction