extension is not called

<?php  if ( ! defined('EXT')) exit('No direct script access allowed');

/*
=====================================================
 By: Yuriy Salimovskiy
-----------------------------------------------------
 http://www.intoEEtive.com
=====================================================
*/

class Deposit_ext {

    var $settings        = array();
    var $name            = 'Deposit extension';
    var $version        = '0.1';
    var $description    = 'Add funds to member\'s account.';
    var $settings_exist    = 'n';
    var $docs_url        = 'http://www.intoeetive.com/';
    

    /**
     * Constructor
     */
    function Deposit_ext($settings = '')
    {
        $this->settings = $settings;
    }

    // --------------------------------------------------------------------
    
    /**
     * Register hooks by adding them to the database
     */
    function activate_extension()
    {
        global $DB, $PREFS;    
        
        $hook = array(
                        'extension_id'    => '',
                        'class'            => __CLASS__,
                        'method'        => 'add_funds',
                        'hook'            => 'simple_commerce_perform_actions_end',
                        'settings'        => serialize($settings),
                        'priority'        => 10,
                        'version'        => $this->version,
                        'enabled'        => 'y'
                    );
        $sql[] = $DB->insert_string('exp_extensions',    $hook);
        
        foreach ($sql as $query)
        {
          $DB->query($query);
        }
    }
    
    // --------------------------------------------------------------------
    
    /**
     * add funds
     */
    function add_funds( $scobject, $row )
     {
         global $DB, $SESS, $PREFS, $REGX;
         
                         if ( ! class_exists('EEmail'))
                {
                    require(PATH_CORE.'core.email.php');  
                }    
                

                    $subject = 'test subject';
                    $message = 'test message';
                    

                    
                    $MAIL = new EEmail;
                    $MAIL->from($PREFS->ini('webmaster_email'));
                    $MAIL->to('[email protected]');
                    $MAIL->subject($subject);
                    $MAIL->message($REGX->entities_to_ascii($message));
                    $MAIL->Send();
     }

    

    
    // --------------------------------------------------------------------
    
    /**
     * No updates yet.
     * Manual says this function is required.
     * @param string $current currently installed version
     */
    function update_extension($current = '')
    {    
        return TRUE;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Uninstalls extension
     */
    function disable_extension()
    {
        global $DB;
        $DB->query("DELETE FROM exp_extensions WHERE class = '".__CLASS__."'");
    }
    
    // --------------------------------------------------------------------
    
    /**
     * EE extension settings
     * @return array
     */
    function settings()
    {
        $settings = array();
        return $settings;
    }

    
}
// END CLASS
?>