Free extensions for Joomla!

I love xmap! But by rebuilding my webshop there is a mistake that I can not understand. I built a sitemap with virtuemart plugin activated and the sitemap looks okay - also for the single produkts.
But when I enter the sitemap URL in Google webmasters tools the crawler brings tons of 404 errors that are all because of product pages. I compared the URL in the Sitemap with the URL that caused an 404 error:

URL on website and in the xmap sitemap:
http://www.tiramizu.de/index.php/virtuemart/kleine-leute/spielen-und-lernen/piratenschiff-totenkopf-detail

Crawling bug on Google webmasters tools:
http://www.tiramizu.de/index.php/de/component/virtuemart/kleine-leute/spielen-und-lernen/piratenschiff-totenkopf-detail?Itemid=0

I Do not understand where this wrong URL comes from and how to fix this problem?

I Use J! 2.5.3 and VM 2.0.2, xmap 2.2.1

Any idears?