Adding a DB to Configuration Extensions

Hi Team, I have two questions.

While adding a db to configuration extensions, I get the error: The DB Credential Set is missing entries for for the following target "db_name".

What am I missing, is there a way to check which credentials I am missing?

2) After migrating a few db to a new server with a new name, targets show up, however when querying : SELECT * FROM SYSMAN.EM_MANAGEABLE_ENTITIES WHERE ENTITY_TYPE='oracle_database' and promote_status=3 and manage_status='2';

I notice that the host_name is pointing to the old host where the db's used to run.