Alarm couldn't be acked in Redundancy

Dear Phantom75:
(1)I use WinCCv62+sp2 asia
(2)And my configuration oh the alarm logging is like this list,the coming alarms is red color,the went alarms is green,the acked alarms is yellow,when the alarms triggers,the coming alarms is red,and i ack the coming alarms should become yellow,but it's still red and not change color,one server is ok to ack,other server is not ok to do it.then i try to restart the wincc,sometimesthe 2 servers become ok,sometimes not.

Best Regards

Buzz LightYear