No Forest Trust Option at 2003 Functional Level

I am trying to create a forest trust in a lab using the MS education
curriculum setup. Both domains have been raised to 2003 functional level
via AD domains and trusts tool. When I attempt to add the new trust the
forest option is missing. The userid is a member of Enterprise Admins and
Domain Admins.

What can I check to see what might be wrong? I can't see any related errors
in the system event logs or directory logs on either DC.