I've noticed that with my sitemapindex.xml and the subtending xml's, my primary domain is not listed. Is this OK, or did I make an error somewhere?

Most of my subdomain pages are listed and ranking decently, but my primary domain has not been indexed. And, I've built more anchored links to this primary domain name than my subs. any ideas what's happening here?

This is the site: www. bigb erke ywate rfilt ers.com

Thanks!