Placing users into Power User group across domains

At a client, we are moving from a single domain to a multiple domain model.

The Local City office has all the machines joined to the Local_City_Domain.  The National_Offices_Domain contains all the uer accounts.  There is a one way trust where the Local_City_Domain trusts the National_Offices_Domain.  Users log on to the machines with the National_Offices_Domain from the drop down list.

We have to place the National_Offices_Domain members into the local laptop Power Users group to allow them to manage IP addresses (some locations have only static addresses), set power setting behavior, change what happens when they close the lid of their laptops and the like.

I had thought that this would be as easy as logging on to the laptop with the domain admin account of Local_City_Domain, opening up  Local Groups, adding members to the Power User group using either National_Offices_Domain\username or National_Offices_Domain\usergroup (where the group "usergroup" is a Global Group created in the National_Offices_Domain) or by changing the search parameters to the correct domain and typing in the user name or the group name.

When I do this, the machine goes out and thinks for a bit and comes back suggesting that I change the way I have set up the username or group name, but never resolves the correct name to add to the Power User group.

Did I misunderstand how these types of Resource/User domain scenarios are set up?  Am II missing something basic?

Thank you in advance.Start Free Trial