无法在Symfony2中加载第三方类

My main problem is, that i dont have access to Solarium (a third party libary) in my symfony2-project and I do not understand why. I have a symfony2 application and want to write my own Solr connector. Therefore I want to use Solarium. (IMPORTANT: I dont want to use other bundles for this)

First I installed it via composer

"require": {
        //...
        "solarium/solarium": "3.3.0.x-dev"
    }

Then i called:

php composer.phar install

php composer.phar update

Second i created a new directory for my connector in my bundle:

/src/COMPANY/ThatIsMyBundle/SolrSearch/

In this directory is my class SolrConnector.php

namespace COMPANY\ThatIsMyBundle\SolrSearch;

use Solarium\Client;
//use Solarium\Core\Client;

class SolrConnector {
        private $solr_client;
        function __construct($settings)
        {
            $solr_config = array(
                'endpoint' => array(
                    'protokolldb' => array(
                        'host' => $settings['solrHost'],
                        'port' => $settings['solrPort'],
                        'path' => $settings['path'],
                        'core' => $settings['core'],
                        'timeout' => $settings['timeout']
                    )
                )
            );
            $this->solr_client = new Client($solr_config);
        }

         /**
         * Check if Solr is on.
         */
       function executePing() {
            $ping = $this->solr_client->createPing();
            try {
                $this->solr_client->ping($ping);
                echo "Solr is fine.
";
            } catch (Exception $e) {
                echo "Solr is unaccessible. Look up whats wrong with Solr and restart this script.
 ".$e->getMessage();
            }
        }

    }

I got this error message from symfony:

Attempted to load class "Client" from namespace "Solarium" in "(my specific path to the project)/SolrSearch/SolrConnector.php line 32." Do you need to "use" it from another namespace?

What i have to do to use Solarium in my Symfony2 Bundle? I think it is a namespace/use/require problem. I googled it for hours... with no solution.

Things i tried:

adding

require('../vendor/autoload.php);

same error.

When you use

php composer.phar install

it only install packages stored in composer.lock

You need to run

php composer.phar update

to install new packages. It also clear and warm up symfony cache and autoloader