Server Administration :: Get Details Of SYS / SYSTEM Users Logon And Logoff Time

I want to get the details of the SYS/SYSTEM users logon and Logoff's time.

Steps 1:
=======
SQL> SHOW PARAMETER AUDIT

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
audit_file_dest string C:ORACLEPRODUCT10.2.0ADMIN
DB10GADUMP
audit_sys_operations boolean FALSE
audit_trail string NONE
SQL>

Step 2:
=======
Set the Necessary parameters:
-----------------------------
alter system set audit_trail=db scope=spfile;

Step 3:
=======
Shutdown the DB

Step 4:
=======
Restart the DB

Step 5:
=======
For auditing the Session. Fire the below command.

AUDIT CREATE SESSION;

Step 6:
=======
select DISTINCT USERNAME,os_username,timestamp,logoff_time
from DBA_audit_session;

When I fire the above query, I couldn't get the SYS user's LOGOFF time. But for rest of the users, I am getting.