webmastertools shows error with news sitemap xml-tag missing

Hi!

The regular sitemap at http://www.mrn-news.de/sitemap.xml shows normal and also is accepted by webmastertools.

But when I try to submit the sitemap-news.xml to google’s webmastertools it says:

Error. Missing XML-tag urlset/url. Please add tag and resubmit.

Also the sitemap doesnt show anything except “<urlset/>” when I view it over the browser.

Help would be appreciated!

View the sitemap at:
http://www.mrn-news.de/sitemap-news.xml

https://wordpress.org/plugins/xml-sitemap-feed/