[Plugin: Google XML Sitemaps] Google site map error

I sumbit my site map(one of multisite) with the plugin version 4.0beta10 and gives me this msg:
Missing XML tag
This required tag is missing. Please add it and resubmit.
1
Sitemap: /sitemap-pages-2011-10.xml
Parent tag: urlset
Tag: url
4
Oct 11, 2012

What is wrong?

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