Symptom:
During the WEM HA testing we notice failover on an active Alarm received on server 1, does not get cleared on the NB system when clear received on Server2. However the alarm is clear in the WEM.  For some reason the clear  message does not get sent to NB system from the WEM.

Conditions:
The NB alarm raise and clear notification is working.  The only instance where it is not working is:
Active Alarm X in WEM1
Failed over initiated
Active alarm X failed over to WEM2
Alarm X cleared in WEM2, but no NB notification (per TCPdump) to NB server. 
Note that subsequent alarms are working after fail over.
Alarm Y raised in WEM2 and NB.
Alarm Y cleared in WEM2 and NB.

Summary: Clearly it is WEM issue here after fail over.  Same behavior on both WEM servers.