When I do a dig I'm seeing an SOA only for NS1. Whether that's because NS2 is down or because the SOA record just doesn't exist, I don't know. Either way, an admin will need to fix the issue with NS2. For the time being, contact the registrar and ask them to set the NS for you, telling them that your host only provides one (working) NS. We've had at least 1 other person with the same issue, and they were able to set it up by contacting the registrar. Alternately, you could create an A record to 216.218.192.170 instead. You already have your domain set as your Heliohost account's main domain, so this should work without any additional configuration.