"alter session set "_swrf_test_action" = 72" does not work on my DB, old AWR cannot be purged

Hi DBAs,

I need some help here, I'm currently running with several Oracle 11.2.0.3/4 database on HP UNIX,and SYSAUX tablespace's size always grows, so I followed ID 387914.1 to split my AWR data into smaller partitions and to drop those partition out of date, however, "alter session set "_swrf_test_action" = 72"  never works on my DBs, It returns no error and no trace file, but I just cannot see any new partion created after the "_swrf_test_action", for example WRH$_ACTIVE_SESSION_HISTORY still has only one patrtion contains all awr data before, "_swrf_test_action" = 72  only adds new empty partiotion on the table.