New extension don't work

I want to detect when a new user register in my web by the pluggin Nextend Facebook Connect. For that, I made a new extension, but it don’t shows in the event list. I need to do something more?

<?php
/**
 * Extension for nextend facebook conect

 * This file extends Achievements to support actions from Nextend facebook conect.
 *
 * @package Achievements
 * @subpackage ExtensionNextendFacebookConnect
 */

// Exit if accessed directly
if ( ! defined( 'ABSPATH' ) ) exit;

/**
 * Extends Achievements to support actions from WordPress (core).
 *
 * @since Achievements (3.0)
 */
function dpa_init_nextend_facebook_connect_extension() {
	achievements()->extensions->nextend_facebook_connect = new DPA_Nextend_Facebook_Connect_Extension;

	// Tell the world that the WordPress extension is ready
	do_action( 'dpa_init_nextend_facebook_connect_extension' );
}
add_action( 'dpa_ready', 'dpa_init_nextend_facebook_connect_extension' );

/**
 * Extension to add WordPress support to Achievements
 *
 * @since Achievements (3.0)
 */
class DPA_Nextend_Facebook_Connect_Extension extends DPA_Extension {
	/**
	 * Constructor
	 *
	 * Sets up extension properties. See class phpdoc for details.
	 *
	 * @since Achievements (3.0)
	 */
	public function __construct() {
		$this->actions = array(
			'nextend_fb_user_registered'     => __( 'A new user register by Facebook.', 'dpa' ),
			'nextend_fb_user_logged_in'      => __( 'A user logins by Facebook.', 'dpa' ),
			'nextend_fb_user_account_linked' => __( 'A user links his Facebook account.', 'dpa' )
		);

		$this->contributors = array(
			array(
				'name'         => 'Vishkey',
				'gravatar_url' => 'http://www.gravatar.com/avatar/24e481cf69e3db980e2aa83a086a5a4a.png',
				'profile_url'  => 'http://profiles.wordpress.org/vishkey'
			)
		);

		$this->description     = __( 'Provides events to Achiviemets with Nextend Facebook Connect.', 'dpa' );
		$this->id              = 'NextendFacebookConnect';
		$this->image_url       = trailingslashit( achievements()->includes_url ) . 'admin/images/nextend.png';
		$this->name            = __( 'Nextend Facebook Connect', 'dpa' );
		$this->rss_url         = 'http://wordpress.org/news/feed/';
		$this->small_image_url = trailingslashit( achievements()->includes_url ) . 'admin/images/nextend-small.png';
		$this->version         = 3;
		$this->wporg_url       = 'https://wordpress.org/plugins/nextend-facebook-connect/';

		add_filter( 'dpa_handle_event_user_id', array( $this, 'event_user_id'), 10, 3 );
	}

	/**
	 * For the comment_post and post publish events, swap the logged in user's ID
	 * for the post's author's ID. This is to support post moderation and publishing
	 * by other users.
	 *
	 * @param int $user_id
	 * @param string $action_name
	 * @param array $action_func_args The action's arguments from func_get_args().
	 * @return int|false New user ID or false to skip any further processing
	 * @since Achievements (3.0)
	 */
	public function event_user_id( $user_id, $action_name, $action_func_args ) {
		// Only deal with events added by this extension.
		if ( ! in_array( $action_name, array('nextend_fb_user_registered') ) )
			return $user_id;

		// New user registration
		if ( 'nextend_fb_user_registered' === $action_name ) {
			return $action_func_args[0];
		}
	}
}

https://wordpress.org/plugins/achievements/