Sitemap Error at webmaster tools

Hello guys, I have submitted this http://www.globaladverts.biz/sitemap_index.xml sitemap at google and bing webmaster tools which consist of the following sitemaps:-
http://www.globaladverts.biz/post-sitemap.xml
http://www.globaladverts.biz/page-sitemap.xml
http://www.globaladverts.biz/ad_listing-sitemap.xml
http://www.globaladverts.biz/ad_cat-sitemap.xml
http://www.globaladverts.biz/category-sitemap.xml
http://www.globaladverts.biz/ad_tag-sitemap.xml

I have excluded the following taxonomies in my sitemap beacause i dont want them to appear on search engines:-

Catogies
Tags
Format
Ad tags

After disabling those the above taxonomies am only using the following sitemaps:-
http://www.globaladverts.biz/post-sitemap.xml
http://www.globaladverts.biz/page-sitemap.xml
http://www.globaladverts.biz/ad_listing-sitemap.xml
http://www.globaladverts.biz/ad_cat-sitemap.xml

At first all of the of the sitemaps seem to work just fine but recently while checking on google and bing webmaster tools I saw the following errors on this http://www.globaladverts.biz/ad_cat-sitemap.xml sitemap and the following is the error I encountered in each of the webmaster tools:-

In Bing it gives me that The feed was empty
In google webmaster tools it tells me that Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead.

Also another problem am encountering is that bing webmaster tools it shows all the sitemaps including the ones i have disabled.

Is there a way to fix this? Please help me guys.

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