If %ServerName; is configured to use NETBIOS, specify the NETBIOS name. Otherwise specify the DNS name of the workgroup computer. ...

1. If %ServerName; is configured to use NETBIOS, specify the NETBIOS name. Otherwise specify the DNS name of the workgroup computer. OR
2. Ensure that the user account exists on this server or specified protected computer name is correct. OR
3. Ensure that the specified server has been configured for non domain protection. OR
4. The caller is an admin on the server.