Hi Anders,

yes the demo site is working fine using the Joomla multilanguage. See the screenshots for english and french. Of course there are only few demo contents with multilanguage on this demo site.

Also looked at your site, generated the sitemaps in both language and all works as it should, you have 2 languages and so 2 sitemaps with different links:
http://www.peltpower.com/index.php/en/?option=com_jmap&format=xml&lang=en
http://www.peltpower.com/index.php/da/?option=com_jmap&format=xml&lang=da

You have to submit both sitemaps, one per each language. If you have configured multilanguage menu this will be the same also for HTML sitemap, eventually ensure that it's not cached. That could prevent language changes.

Regards,

John