phranque - 11:28 am on Oct 24, 2011 (gmt 0)

have you validated your sitemap?

you can read about bing's sitemap-related suggestions here, including the use of sitemap validation.
Bing Uncovering web-based treasure with Sitemaps (SEM 101) - Webmaster Center blog:
http://www.bing.com/community/site_blogs/b/webmaster/archive/2009/08/15/uncovering-web-based-treasure-with-sitemaps-sem-101.aspx [bing.com]