In order to answer this question, the following steps should be taken:

1. Verify the domain functional level
   Check if the domain functional level is appropriate for the scope and characteristics of the Active Directory child domain.
2. Assign rights to the user
   Assign rights to the user in the form of permissions within the child domain.
3. Verify server setup
   Verify that the necessary server infrastructure is properly set up and running in the child domain.
4. Verify replication
   Verify that the replication between the child domain and other domains is functioning correctly.
5. Verify group memberships
   Verify that the user is a member of the proper groups that are authorized to perform the role transfer.
6. Check group policy settings
   Check the group policy settings, particularly for the domain controllers and the schema master, to ensure that the configuration is correct.