Проблема с пространством имен PHP

<?php
 
require_once __DIR__.'/../vendor/autoload.php';
 
use Engine\Cms;
use Engine\DI\DI;
 
 
try {
    //Dependency injection
    $di = new DI();
 
    $services = require __DIR__.'/Config/Service.php';
 
    //Init services
    foreach ($services as $service) {
        $provider = new $service($di);
        $provider->init();
    }
 
    $provider->init();
    $cms = new Cms($di);
    $cms->run();
}catch(\ErrorException $e) {
    echo $e->getMessage();
}

<?php
 
return [
    Engine\Service\Database\Provider::class,
 
];

<?php
 
namespace Engine\Service\Database;
 
use Engine\Service\AbstractProvider;
 
use Engine\Core\Database\Connection;
 
class Provider extends AbstractProvider {
 
    /**
     * @var string
     */
    public $serviceName = 'db';
    /**
     * @return mixed
     */
    public function init() {
        $db = new Connection();
 
        $this->di->set($this->serviceName, $db);
 
        return $this;
    }
 
    public function test() {
        echo '222';
    }
}

<?php
 
namespace Engine\Service;
 
abstract class AbstractProvider {
 
    /**
     * @var \Engine\DI\DI;
     *
     */
    protected $di;
 
    public function __construct(\Engine\DI\DI $di) {
        $this->di = $di;
    }
 
    /**
     * @return mixed
     */
    abstract function init();
}

<?php
 
namespace Engine\DI;
 
class DI {
    /**
    *@var array
    */
    private $container = [];
 
    /**
     * @param $key
     * @param $value
     *
     * @return $this
     */
    public function set($key, $value) {
        $this->container[$key] = $value;
 
        return $this;
    }
 
    /**
     * @param $key
     *
     * @return mixed
     */
    public function get($key) {
        return $this->has($key);
    }
 
    /**
     * @param $key
     *
     * @return bool
     */
    public function has($key) {
        return isset($this->container[$key]) ? $this->container[$key] : null;
    }
 
}