have you tried looking at the routes list that "rake routes" gives you? if your routes.rb is correct, it should show you the correct name for the blog entries route.
also, maybe this can help: http://www.coreywoodcox.com/2008/08/18/rails-namespaces-subdomains/.
edit:
well, then the correct way to call the route is admin_blog_entries_path instead of blog_entries_path.