Identifier "pagerfanta.view_factory" is not defined

Hello,

I'm trying to add this code in my app.php (silex apps)

use FranMoreno\Silex\Provider\PagerfantaServiceProvider;
use Pagerfanta\View\TwitterBootstrapView;

$app['pagerfanta.view_factory'] = $app->share($app->extend('pagerfanta.view_factory', function($viewFactory, $app) {
    $viewFactory->add(array(
        'twitter' => new TwitterBoostrapView()
    ));

    return $viewFactory;
}));

$app->register(new PagerfantaServiceProvider(), array(
    'pagerfanta.view.options'  => array(
        'default_view'  => 'twitter'
    )
));

here is my composer.json :

{
    "require": {
        "silex/silex"           : "^1.2",
        "monolog/monolog"       : "~1.6",
        "doctrine/dbal"         : "~2.3",
        "kriswallsmith/assetic" : "~1.1",
        "mheap/silex-assetic"   : "~1.0",
        "leafo/lessphp"         : "~0.4.0",
        "symfony/console"       : "~2.3",
        "symfony/form"          : "~2.3",
        "symfony/twig-bridge"   : "~2.3",
        "twitter/bootstrap"     : "2.3.2",
        "twig/twig"             : "~1.10",
        "symfony/security"      : "~2.3",
        "pagerfanta/pagerfanta" : "^1.0",
        "franmomu/silex-pagerfanta-provider": "1.0.*@dev"
    },
    "autoload": {
        "psr-4": {
            "Teacup\\": "src/"
        }
    }
}

and I get this error :

Fatal error: Uncaught exception 'InvalidArgumentException' with message 'Identifier "pagerfanta.view_factory" is not defined.'

I don't find what is wrong here; can you help me ?

franmomu / silex-pagerfanta-provider

Identifier "pagerfanta.view_factory" is not defined #10