Modify Lotus Domino CA Administrators

We are trying to create two generic ID files in Domino admin for registering person docs (Registering New users) and re-certify user certificates which are expired. Current issue is we when we create a new person document with ID file and grant access to Admin server and try creating a new lotus domino account, we are unable to view list of certifiers to select.

When we try to modify recovery authorities but it fails and does not resolve the current issue, When we try to Modify certifiers and try to remove administrators its giving an error  “Cannot locate user certificate. Make sure server contains your certificate for encryption”. I also tried copying the person document of that administrator back into their directory and followed the same steps which did not help me.

Can any one help me at the earliest as its very important to us?