sitemaps generates errors in WebMasters dashboard

WordPress version: 3.5.1 MU installed
WordPress SEO version: 1.4.7

I use WordPress SEO on several sites.
I discovered that MU installed sites have errors in the WebMasters Dashboard
– used sitemap = /sitemap_index.xml
– error message :
1 Errors URL not allowed
This url is not allowed for a Sitemap at this location.
1 Sitemap: santa-pola.nl/category-sitemap.xml
URL: http://NieuwsuitSpanjeregioSantaPola

SOmething about the category sitemaps is messed up i think?

Is it a setting or something else?

Any help appriciated.

Hakob.

http://ww.wp.xz.cn/extend/plugins/wordpress-seo/