Problems for autoload class namespace without composer

I've got some problems for register a bundle in a Symfony2 project without Composer.
In my company I can't use Composer due to proxy.

I succesfully install FOSUserBundle so I don't understand why it doesn't work with KnpSnappyBundle...

My vendor tree :

vendor/
    friendofsymfony/
        user-bundle/
            FOS/
                UserBundle/
                    FOSUserBundle.php
    knplabs/
        knp-snappy-bundle/
            Knp/
                Bundle/
                    SnappyBundle/
                        KnpSnappyBundle.php

My app/autoload.php :

<?php

use Doctrine\Common\Annotations\AnnotationRegistry;
use Composer\Autoload\ClassLoader;

/**
 * @var ClassLoader $loader
 */
$loader = require __DIR__.'/../vendor/autoload.php';
$loader->add('FOS', __DIR__.'/../vendor/friendsofsymfony/user-bundle');
$loader->add('Knp', __DIR__.'/../vendor/knplabs/knp-snappy-bundle');

AnnotationRegistry::registerLoader(array($loader, 'loadClass'));

return $loader;

My app/AppKernel.php :

<?php

use Symfony\Component\HttpKernel\Kernel;
use Symfony\Component\Config\Loader\LoaderInterface;

class AppKernel extends Kernel
{
    public function registerBundles()
    {
        $bundles = array(
            new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
            new Symfony\Bundle\SecurityBundle\SecurityBundle(),
            new Symfony\Bundle\TwigBundle\TwigBundle(),
            new Symfony\Bundle\MonologBundle\MonologBundle(),
            new Symfony\Bundle\SwiftmailerBundle\SwiftmailerBundle(),
            new Symfony\Bundle\AsseticBundle\AsseticBundle(),
            new Doctrine\Bundle\DoctrineBundle\DoctrineBundle(),
            new Sensio\Bundle\FrameworkExtraBundle\SensioFrameworkExtraBundle(),
            new My\Bundle\OwnBundle\MyOwnBundle(),
            new FOS\UserBundle\FOSUserBundle(),
            new Knp\Bundle\SnappyBundle\KnpSnappyBundle()
        );

        if (in_array($this->getEnvironment(), array('dev', 'test'))) {
            $bundles[] = new Symfony\Bundle\WebProfilerBundle\WebProfilerBundle();
            $bundles[] = new Sensio\Bundle\DistributionBundle\SensioDistributionBundle();
            $bundles[] = new Sensio\Bundle\GeneratorBundle\SensioGeneratorBundle();
        }

        return $bundles;
    }

    public function registerContainerConfiguration(LoaderInterface $loader)
    {
        $loader->load(__DIR__.'/config/config_'.$this->getEnvironment().'.yml');
    }
}

The error message :

ClassNotFoundException: Attempted to load class "KnpSnappyBundle" from namespace "Knp\Bundle\SnappyBundle" in C:\xampp\htdocs\my-project\app\AppKernel.php line 25. Do you need to "use" it from another namespace?

Please help !

OK I found it !

So it was the good procedure but I forget to clear the cache.

php app/consoloe ca:cl -e=dev

After that I've still got an error :

Fatal error: Interface 'Knp\Snappy\GeneratorInterface' not found in /vendor/bundles/Knp/Bundle/SnappyBundle/Snappy/LoggableGenerator.php on line 14

Because without Composer a part of the KnpSnappyBundle is missing, so I download the missing directories on GitHub and add in my vendor :

vendor/
    knplabs/
        knp-snappy-bundle/
            Knp/
                Bundle/
                    SnappyBundle/
                        KnpSnappyBundle.php
                Snappy/
                    Exeption/
                    AbstractGenerator.php
                    GeneratorInterface.php
                    Image.php
                    Pdf.php
                    Process.php

Everything works, I didn't modify my app/autoload.php and my app/AppKernel.php.