[Plugin: WordPress SEO by Yoast] Sitemap: Google Webmaster 403

Greetings,

I’m getting the 403 error for all links submitted to google via the generated sitemap.

Thought it might be the robots.txt but well this file doesn’t even exist on my server so might it be the htaccess file?

I for one can reach the file without an error:
http://jdbartist.net/sitemap_index.xml

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