In a recent discussion held in Google webmaster help, a webmaster raised an issue related to his website sitemap URL. None of his URLs submitted by him using XML sitemap file were indexed by Google. Obviously, this isn’t an individual’s case but alarming for any webmaster. Google’s Zineb said following why Google Refuses To Index Sitemap.
“All the URLs listed in your XML Sitemap are non www. And they all permanently redirect to the www. Version (which is your preferred domain). That explains why these specific URLs are not indexed. In order to fix that, you’ll need to specify the right URLs with www. Resubmit your Sitemap and wait for it to be processed again.”
You should be very careful when you submit Sitemap file. If you verify a non-www version of URL with Google webmaster tool and submit a www-version or vice versa, Google refuses to listen. So, this time when you are going to do so, be careful. It’s easy to fix but demands caution.