Correct, I used the exact nameservers HelioHost provided on their site, and separately placed both in each of the Nameserver boxes for that domain.
My domain is http://www.elixium-x.com/ and my user account name is elixiumx. And like I said, it has worked before, and even seconds after I initially put the new Nameservers into the domain name, the site was up and running. It stopped working, without reason, about a week into it, and I hadn't changed any of the files during that time period.