Why am I not able to set up trust authentication between two different Active Directory forests?

1. Ensure that an appropriate trust relationship exists and is working between the two forests; this includes enabling the two-way transitive trust
2. Verify that the same Kerberos realm is being used by both forests
3. Confirm that the necessary DNS records are in place and correct
4. Ensure that Active Directory is operating properly and that any necessary schema updates for the trust relationship have been completed properly
5. Verify that the correct security settings have been applied to the trust
6. Ensure that all authentication settings and protocols are correctly configured.