Error plugin gallery in article

Content - Photo Gallery Plugin content / photogallery Hot Photo Gallery - Commercial plugin from HotJoomlaTemplates.com Catchable fatal error: Object of class JDocumentHTML could not be converted to string in /home/u378378821/public_html/plugins/content/photogallery/elements/loader.php on line 40

<?php /** * @version $Id: text.php 15576 2010-03-25 12:43:26Z louis $ * @package Joomla.Framework * @subpackage Form * @copyright Copyright (C) 2005 - 2010 Open Source Matters, Inc. All rights reserved. * @license GNU General Public License version 2 or later; see LICENSE.txt */ defined('JPATH_BASE') or die; jimport('joomla.form.formfield'); /** * Form Field class for the Joomla Framework. * * @package Joomla.Framework * @subpackage Form * @since 1.6 */ class JFormFieldLoader extends JFormField { /** * The form field type. * * @var string * @since 1.6 */ protected $type = 'Loader'; /** * Method to get the field input markup. * * @return string The field input markup. * @since 1.6 */ function getInput(){ $document = JFactory::getDocument(); $header_media = $document->addStyleSheet(JURI::root(1) . '/plugins/content/photogallery/css/admin.css'); $header_media .= $document->addScript(JURI::root(1) . '/plugins/content/photogallery/js/jscolor.js'); } }