The domain nameservers are set correctly to x10 but these are not pointing it anywhere. Check in your cPanel under Subdomains to see whether it has appeared there. If so, delete the subdomain completely then try in Addon Domains to add the domain again from scratch. This worked for someone else with the same problem yesterday. If it does not appear as a Subdomain then you need an Admin to assist in setting it up properly on the x10 nameservers.