UNDP Alert configuration.

HI, 

We have Configured UNDP poller to monitor BFD session on cisco vEdge devices and if looks fine too. customer want an alert when X No. of sessions go down on any device.

we have configured an alarm rule to generate an alert with help of advance option with condition if X No. of event occurs. 

its working fine for one device but in case of multiple devices it is taking calculative value and generating alert even  down session is with in threshold on all devices. 

please suggest, how can we configure an alert to  monitor  BFD  sessions effectively on all vEdge devices. 

configured alarm rule condition is as below.