[Plugin: Google XML Sitemaps] Notice: Undefined index on line 1510 – debug

Hi,
I checked the debug mode and found this error :

Notice: Undefined index: class in /home/www/rmvalues.com/blog/wp-content/plugins/google-sitemap-generator/sitemap-core.php on line 1510

The code is :

if($b[“class”] != __CLASS__) {

Also, how to manually rebuild the sitemap ?

http://wordpress.org/extend/plugins/google-sitemap-generator/