[Plugin: WordPress SEO by Yoast] Webmaster tools telling me xml site map is html

Hi,

Im using the yoast plugin (obviously) to generate my xml sitemaps. I submitted them to Google through Webmaster tools and I’m presented with an error telling me that the site map is html and that I should use a supported version.

What should I do? any way I can fix this? http://www.montessoricommons.cc

Thanks for your help 😀

http://wordpress.org/extend/plugins/wordpress-seo/