Access-Control-Allow-Origin problems on the same domain
It probably is because of the missing www. If you test with yourdomain.com and your site is at www.yourdomain.com it is concidered cross-domain and cross-domain calls are not allowed by default.
1) look in your request/response headers. Is the server returning a weird access-control-allow-origin header?
2) It's not just the domain, it's also the protocol (http vs https vs ftp etc), the port (if you have a :8080 or something like that), and potentially the part after the .com/