Help with Felx.IDLE event

for setting one minute timeout interval I using following formaula

private var TS_USER_CAN_BE_IDLE:uint = (60 * 20 * 10);

below is my logout code

private function no_user_activity_handler(event:FlexEvent):void

                    {

                              if (event.currentTarget.mx_internal::idleCounter > TS_USER_CAN_BE_IDLE)

                              {

                                        trace("^^^^^^^^^^^ idleCounter " + event.currentTarget.mx_internal::idleCounter);

                                        trace("^^^^^^^^^^^ TS_USER_CAN_BE_IDLE " + TS_USER_CAN_BE_IDLE);

                                        this.stopSessionTracking();

                                        logout_user();

                              }

                    }

when browser window is minimized, logoutUser method is called after inteval 5 times greater than the TIME_OUT_LIMIT. Can you tell me what's wrong I am doing.