ora-04098 trigger is invalid and failed re-validation

[ali560045]

I have a Trigger that will fire whenever any DDL statement is executed.Below the trigger code

create or replace trigger
   DDLTrigger
AFTER DDL ON DATABASE
BEGIN
insert into
   perfstat.stats$ddl_log
(
   user_name,
   ddl_date,
   ddl_type,
   object_type,
   owner,
   object_name
)
VALUES
(
   ora_login_user,
   sysdate,
   ora_sysevent,
   ora_dict_obj_type,
   ora_dict_obj_owner,
   ora_dict_obj_name
);
END;

When i m testing this trigger by truncating a table i m getting ORA-ERROR as
"ora-04098 trigger is invalid and failed re-validation"

How should i solve this issue ?

[PAVB]

Have you created the trigger as SYS?

Please execute and post...

select * from dba_objects where object_name in ('DDLTRIGGER','STATS$DDL_LOG');

[ali560045]

No, i have created the trigger as USER . Below is what i get when i logon as SYS and do the following commands

select * from dba_objects where object_name in ('DDLTRIGGER','STATS$DDL_LOG');

OWNER	OBJECT_NAME	SUBOBJECT_NAME	OBJECT_ID	DATA_OBJECT_ID	OBJECT_TYPE	CREATED	LAST_DDL_TIME	TIMESTAMP	STATUS	TEMPORARY	GENERATED	SECONDARY
SCOTT	DDLTRIGGER		30,359.00		TRIGGER	05/20/2009 18:07:36	05/20/2009 18:07:36	2009-05-20:18:07:36	INVALID	N	N	N
SCOTT	STATS$DDL_LOG		30,347.00	30,347.00	TABLE	05/20/2009 15:39:43	05/20/2009 15:39:43	2009-05-20:15:39:43	VALID	N	N	N

[PAVB]

No, i have created the trigger as USER

DDLTrigger is supposed to be a system level trigger -create it as SYS.