A user account from Domain A cannot authenticate to a server in Domain B.
The trust between the two domains may not be established properly.
Verify that the trust exists between the two Domains:
From your Domain Controller or a workstation where Administrative Tools for the domain are available:
- Click "Start", "Programs", "Administrative Tools" and select "Active Directory Domains and Trusts". Right-click the appropriate domain name, select "Properties", and then select the "Trusts" tab.
If the Trust does not exist, it will need to be created in order for cross-domain authentication to work:
- Click "New Trust..." and use the New Trust Wizard to create the new trust. Please refer to the appropriate Microsoft documentation for steps on creating Trusts.
See "What Are Domain and Forst Trusts?": http://technet.microsoft.com/en-us/library/cc757352.aspx