The problem is when you type your domain name in address bar without www it gives 404 error and not redirecting to your www.yourdomain.com.
- After loging to your account click on My Account button.
- In Domain tab click Launch.
- Check the checkbox near to your domain and from the above menu choose Forward to domain option.
- It will show a window asking to type a domain name with www.yourdomain.com for your naked domain yourdomain.com.
- Type in the field provided your full domain name eg. www.yourdomain.com, you can click the preview button to check the forwarding site.
- After confirmation click on OK and make sure the Auto DNS Update check box is checked.