IndexController handler class cannot be loaded

Hello! I'm having a problem (i hope i picked the right category) when i'm trying to use namespaces in my app. I have created a very basic app and i reproduce the issue there. I am new in phalcon and i'm working with 2.0.6.

This works :

(loader.php)

<?php

$loader = new \Phalcon\Loader();

$loader->registerDirs(array(APP_PATH . $config->application->controllersDir));

//$loader->registerNamespaces(array('Test\Controllers' => APP_PATH . $config->application->controllersDir));

$loader->register();

(IndexController.php)

<?php

//namespace Test\Controllers;

class IndexController extends \Phalcon\Mvc\Model {

    public function indexAction() {
    }
}

And this (what i'm trying to do) not :

(loader.php)

<?php

$loader = new \Phalcon\Loader();

//$loader->registerDirs(array(APP_PATH . $config->application->controllersDir));

$loader->registerNamespaces(array('Test\Controllers' => APP_PATH . $config->application->controllersDir));

$loader->register();

(IndexController.php)

<?php

namespace Test\Controllers;

class IndexController extends \Phalcon\Mvc\Model {

    public function indexAction() {
    }
}

Any ideas?