auto stat configuration

I am having trouble configuring 'auto optimizer stats collection' to work on Oracle 11.2.0.2 on HP-UX. The other two auto tasks are running fine. I have successfully configured this in DEV.

Statistics level is set to TYPICAL and I am logged in as SYS:

SQL> exec dbms_auto_task_admin.enable('auto optimizer stats collection',null,null);

PL/SQL procedure successfully completed.

SQL> select CLIENT_NAME,STATUS from dba_autotask_operation;

CLIENT_NAME                      STATUS
-------------------------------- --------
auto optimizer stats collection  DISABLED
auto space advisor               ENABLED
sql tuning advisor               ENABLED

Querying DBA_AUTOTASK_WINDOW_CLIENTS shows that the stats job is enabled in the desired windows: