Sitemap didnt generate correctly

The first thing I did with this plugin was to generate a sitemap. However of the 11 sitemaps generated by this plugin in the sitemap index file, only 5 of the 11 were actually there. The missing 6 caused Google Webmaster Tools ( when sitemap submitted ) to return ‘General HTTP error:404 not found’ error messages and Google asked me to re-submit the sitemap index file so that it follows their guidelines. I can’t comment on the other functionality of the plugin but the first and only function I asked it to perform was a big fail.