[Plugin: Google XML Sitemaps] URL issue with WordPress Mu 2.9.2

On WordPress Mu file is saved at /home/user/wordpress-mu/wp-content/blogs.dir/2/files so it seems not reacheable in neither of WPMu domain options: blog.site.com/sitemap.xml or site.com/blog/sitema.xml

Any hint on how to solve this?

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