sitemap question

My sitemaps are generated with this file name for example (sitemap_forum_1.xml.gz)
I tried submitting these to my webmaster tools account in google but it cannot read these files.

I know the script is supposed to notify search engines automatically but why can't google read these files

http://legalhelp.org/sitemap_index.xml.gz
is the only file you should submit to google. Everything else is linked from here.