我在用户变量中得到空值..我错过了什么????
PrincipalContext pc = new PrincipalContext(ContextType.Machine);
GroupPrincipal user = GroupPrincipal.FindByIdentity(pc, @"NT AUTHORITY\NETWORK SERVICE");
GroupPrincipal group = GroupPrincipal.FindByIdentity(pc, "Administrators");
group.Members.Add(user);
group.Save();