When adding a domain to Helm, it fails and I get the following error in the log:
2007-06-28 12:23:21 modNTUsers.AddUserToGroup 0-2147023509: Automation error
A member could not be added to or removed from the local group because the member does not exist.
Check your Server Name in Helm. It should NOT be a fully qualified domain name. For instance, if your server is called "ns1.myserverdomain.com" then in Helm, you only need to put NS1.
This is because the WIN32 API is failing when you use a FQDN. The API uses RPC to perform the functionality, and that uses NetBIOS or host names. If you use a FQDN then it is likely to look outside of the server, and then back in again - and in most cases on the way back in the ports will not be accessible, hence the failure.
Just remove any ".domain.com" after the server name in Helm, and save. If you still have issues, contact your support provider.