Just ran into this (unlucky) error...
Paths don't match
We've detected that you submitted your Sitemap using a URL path that doesn't include the www prefix (for instance, http://example.com/sitemap.xml). However, the URLs listed inside your Sitemap do use the www prefix (for instance, http://www.example.com/myfile.htm).
I had to go and create 14 more entries for my works domains cause once an entry is created, it can't be modified. Thank you Google webmaster tools, I'm sure that doing the right thing would have been such a chore to code up.