// setup a current URL variable for this script
                $this_script = 'http://' . $_SERVER['HTTP_HOST'] . '/payments/index';
                $settings = site_settings();

                CRV_PayPalClass::add_field('business', $settings->paypal_email);
                CRV_PayPalClass::add_field('return', $this_script . '/action/success');
                CRV_PayPalClass::add_field('cancel_return', $this_script . '/action/cancel');
                CRV_PayPalClass::add_field('notify_url', $this_script . '/action/ipn');
                CRV_PayPalClass::add_field('item_name', 'Administrative Fee');
                CRV_PayPalClass::add_field('amount', $settings->listing_fee);
                CRV_PayPalClass::add_field('currency_code', 'USD');
                CRV_PayPalClass::add_field('custom', $this->listingID);
                CRV_PayPalClass::add_field('cmd', '_xclick');
                CRV_PayPalClass::add_field('rm', '2');

                CRV_PayPalClass::submit_paypal_post();
                // submit the fields to paypal
                break;

            case 'success' :

                redirect('/users/mylistings');

            break;

            case 'cancel' :

                $this->load->view('header');

                echo _('Canceled listing');

                break;

            case 'ipn' :
                if (CRV_PayPalClass::validate_ipn()) {
                    $listingID = abs(intval($_POST['custom']));
                    $this->db->update("listings",
                                    array("list_expires" => strtotime("+1 Month"),
                                         "listing_status" => "active"),
                                    array("listingID" => $listingID));
                }
                break;
        }

        ob_end_flush();
    }