Trigger issue

I have a user that only should grant specific ROLES to other users.

I created a trigger in order to restrict AFTER GRANT event but I am getting the following error: “ORA-00406: COMPATIBLE parameter needs to be 8.1.6.0.0 or greater”

Running :
select value from v$parameter where name ='compatible';
I got: 8.1.0
But I am not sure if I should change it and which is the recommended procedure.   (QUESTION 1)

The trigger is:

CREATE or REPLACE TRIGGER prohibit_grant_SAUABC
BEFORE GRANT on SAUABC.schema
BEGIN
IF ora_sysevent='GRANT' and ora_dict_obj_type = 'ROLE'
THEN
RAISE_APPLICATION_ERROR(-20005,'You are not allowed to grant this role');