I have a new blog at glowingstart.com (didn't want to add it to the question, but the domain is needed to verify that it can't be crawled by that sitemap-generating site) and I was trying to use this site http://www.xml-sitemaps.com/ to create a sitemap. I have created sitemaps for other sites there and it worked fine.
But with this new site, I got an error. Is there some setting which prevents crawling that Wordpress has? Or what may be the reason for this?