rows of DBA_AUDIT_TRAIL not visible in AUD$
I had an Oracle 9i database using auditing in DB. A procedure was used to delete some rows from SYS.AUD$ (because for example: we audit failed logons, but a "polling program" performs 'connect dummy_user/dummy_password' every 5 minutes to check return code. So we have to discard these records).
Everything was fine with 9i (9.2.0.7). Database has been migrated to 10g (10.2.0.4) and now I can not see the records in SYS.AUD$ (even connected with SYS), although I see them in DBA_AUDIT_TRAIL. I see only the records inserted before the migration 9i-10g. I don't understand this mystery and I am afraid SYS.AUD$ will grow up without control.