Alert not showing in database control

My database version 11gR2.

In databse control (Enterprise Manager not Grid control), I have the Tablespace Space Used (%) metric set to Critical Threshold 97% and Warning Threshold
85%
To test, I have created a tablespace and fill it with data until raise the Tablespace
Space Used (%) alert.
The problem is that alert is not showing in database control. Any idea?
Thank you,

BEGIN
*
ERROR at line 1:
ORA-01653: unable to extend table DBA_U.TEST_TRAP_SNMP by 8 in tablespace TSPACE_TEST
ORA-06512: at line 3
SQL>
SQL> SELECT REASON
, METRIC_VALUE
, MESSAGE_TYPE
, TO_CHAR(CREATION_TIME,'DD-MON-YYYY HH24:MI:SS') AS CREATION_TIME,
HOST_ID
FROM SYS.DBA_OUTSTANDING_ALERTS; 2 3 4 5 6

REASON                                         METRIC_VALUE MESSAGE_TYPE
CREATION_TIME                            HOST_ID
---------------------------------------------- ------------ ------------
---------------------------------------- --------------------
Tablespace [TSPACE_TEST] is [100 percent] full          ### Warning
29-AUG-2011 01:09:45                     db01

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