This problem is related to authentication. With Windows Authentication, the users' permissions are used to gain access to the Simplify database. This works for the primary domain because when the Simplify database is generated, NT Authority\Authenticated Users are granted 'Connect' and 'Read' access to the Simplify database. NT Authority\Authenticated Users does not work for trusted domains, unless the trusted domain resides in the same forest as the primary domain. This can be resolved by switching to SQL Authentication or granted Domain Users from the trusted domain access to the Simplify database.