Zend\Permission\Acl class not found

im using zend acl with composer.other zend classes(such as zend config...) are working well but when i try zend acl it says fatal error: Zend\Permission\Acl not found....

code:

use \Zend\Permissions\Acl\Acl; use Zend\Permissions\Acl\Role\GenericRole as Role; use \Zend\Permissions\Acl\Resource\GenericResource as Resource;

class Test extends MY_Controller {

public function __construct() {
    parent::__construct();

}

public function index()
{


  $acl = new Acl();

 $acl->addRole(new Role('guest'))
->addRole(new Role('member'))
->addRole(new Role('admin'));

 $parents = array('guest', 'member', 'admin');
 $acl->addRole(new Role('someUser'), $parents);

 $acl->addResource(new Resource('someResource'));

 $acl->deny('guest', 'someResource');
 $acl->allow('member', 'someResource');

 echo $acl->isAllowed('guest', 'someResource') ? 'allowed' : 'denied';

  }

}

any idea?

help me...