Christian is right you need to see the SQL.
You should not get a ORA-00001 error on a delete so it is doing something your not expecting, and the SQL will show your that.
Could you be deleting a record than inserting a recond with the key you just deleted? If the delete is failing you could get the error.
PS in Oracle ABC2 does not equal abc2 it is case sentitive. But are you messing up on the case when tring to delete it? This could also be part of the problem above.