MM error: undefined - undefined (started 14 Jan 2009)

// The URL to the Jquery library. Leave blank and it will use the one available from jquery.com ...

// Return the HTML necessary to link to the jQuery library
function includeJquery($js_url) {	
	// If no JS url has been supplied, use the Google hosted version
	if (!$js_url || empty($js_url)) {
		$html .= '<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2/jquery.min.js" type="text/javascript" charset="utf-8"></script>';
		$html .= "\n";
	} else {
		$html .= '<script src="'.$js_url.'" type="text/javascript" charset="utf-8"></script>';
		$html .= "\n";
	}
	
	return $html;	
}

    <script src="http://www.google.com/jsapi"></script>
    <script type="text/javascript">
      google.load("jquery", "1.2.6");
    </script>

$js_url = ''; 

$site = $modx->config['site_url'];
$js_url = $site.'assets/js/jquery-1.2.6.min.js';