Silex，没找到上课

I want access of a function in my controller "ItemController". I always have the error; Fatal error: Class 'Iso\Controller\ItemController' not found ...

testsilex / Silex

 - app
 - composer.json
 - src
        - routes.php
        - Iso
            - Controller
                  - ItemController.php

 - vendor
 - web
       - index.php

I have an index.php file in Silex/Web

ini_set('display_errors', 1);
require_once __DIR__.'/../vendor/autoload.php';
$app = require __DIR__.'/../app/app.php';
require __DIR__.'/../src/routes.php';
$app['debug'] = true;
$app->run();

My itemcontroller looks like:

<?php
namespace Iso\Controller;
use Silex\Application;
class ItemController
{
    public function indexAction(Request $request, Application $app)
    {
           echo "it works";
    }
}

My routes.php looks like:

$app->mount('/testsilex/silex/test', new Iso\Controller\ItemController());

My composer.json i added next line:

"autoload": {
        "psr-0": {"Iso": "src/"}
    }

Does anyone know why my class is not found? It will be a small mistake but i can't find it. Thanks :)