Undefined index?

Notice: Undefined property: dcscript_theme::$Smarty in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1820 
Notice: Undefined variable: title in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1879 
Notice: Undefined index: homepage in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1845 
Notice: Undefined index: js in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1882 
Notice: Undefined index: html_head in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1883 
Notice: Undefined index: meta in /customers/4/a/d/jorandesign.nl/httpd.www/login/includes/main.inc.php on line 1884

class dcscript_theme extends Smarty
    {
    var $theme = null;
    function dcscript_theme($theme = null)
        {
        global $dcs_settings;
//// $this->Smarty;
        $this->theme = (is_null($theme) ? $dcs_settings['theme_name'] : $theme);
        $this->activate_theme();
        }

        if ($homepage)
            {
////      $browser_title = str_replace('[site_name]', $dcs_settings['site_name'], $dcs_settings['homepage']['title']);
            }

    function display_page($template, $page_info, $page_name = '')
        {
        global $dcs_settings;
        global $msg;
        $page_filename = substr($_SERVER['REQUEST_URI'], strlen($dcs_settings['site_path']));
        if (preg_match('/^login.php/', $page_filename))
            {
            $page_filename = '';
            }
        $this->assign('msg', $msg);
regel 1879        $this->assign('browser_title', dcscript_theme::browser_title($title, $template == 'homepage.tpl'));
        $this->assign('page_title', $page_info['title']);
        $this->assign('html_css', $page_info['css']);
        $this->assign('html_js', $page_info['js']);
        $this->assign('html_head', $page_info['html_head']);
        $this->assign('html_meta', dcscript_theme::create_meta($page_info['meta']));
        $this->assign('template_name', ($page_name == '' ? $template : $page_name));
        $this->assign('page_filename', urlencode($page_filename));
        $this->assign('login_next_page', urlencode($_SERVER['REQUEST_URI']));
        $this->display($template);
        }