dba_users column Expiry_date not populated, why ?

Hi Everyone,

I try to understand why User ID has got expired status , but expiry_date didn't get populated on dba_users table. Still at Null ?

E.g :

SQL>select USERNAME,ACCOUNT_STATUS,LOCK_DATE,EXPIRY_DATE,CREATED,PROFILE from dba_users where username='TEST';

USERNAME                       ACCOUNT_STATUS             LOCK_DATE    EXPIRY_DATE          CREATED       PROFILE
------------------------------ -------------------------------- ---------------   ------------------       ------------------  ------------
TEST                      EXPIRED                                                                                    18-JAN-2013      TEST_PROFILE

SQL>select * from dba_profiles where profile='TEST_PROFILE';

PROFILE                        RESOURCE_NAME                    RESOURCE LIMIT
------------------------------ -------------------------------- -------- ----------------------------------------
TEST_PROFILE                   COMPOSITE_LIMIT                  KERNEL   DEFAULT
TEST_PROFILE                  SESSIONS_PER_USER                KERNEL   DEFAULT
TEST_PROFILE                    CPU_PER_SESSION                  KERNEL   DEFAULT