Google Webmaster Tools and URL Not Allowed in XML Sitemap
Abstract: You normally have to place your sitemap.xml file in your website root. Placed outside, you may sometimes get errors for pages and URLs in your website. Navigate:Sitemap Generator | Buy | Download | Help Index
Place Your XML Sitemaps in Website Root
Per derfault, Google Webmaster Tools and other search engines only accept URLs in XML sitemaps if:
The URLs are placed in same directory as the XML sitemap.
The URLs are placed beneath the directory where your XML sitemap is placed.
Use XML Sitemap Cross Submit to Solve Problem
If you can edit robots.txt
you may be able to use XML sitemap cross submit as a solution,