Alert Subscriptions - creating subscriptions for groups of computers and alerts from monitors

Question

I've run into something kind of odd.
We want to "tone down" some of our alerts.  Let me explain.
We monitor, roughly, 300 servers.  We created an alert subscription to notify us of alerts for the monitor "Computer Not Reachable".
We found that we often received false positives.  I made sure our check interval was 60 seconds and the heartbeat was set to 3 missed heartbeats and then set the delay to a period of time. 
That worked.  However, we wanted to change the delay based on the server "group".  Example:  Production group and Test Group.  For production, delay 5 minutes, Test, delay 30 minutes.
As soon as tried to add the group criteria to the alert subscription, notifications ceased to function for those alerts.  The alerts still occurred, but the notifications were never delivered.
So, I created new subscriptions and new groups as a test.  Each time, if I included a group in the criteria, the alert notification failed.
Example:
Condition:  Raised by any instance in a specific group.  Checked, group name:  Test
Condition:  created by specific rules or monitors.  checked, monitor:  "Computer Not Reachable"
Subscriber:  [email protected]
Channel:  smtp channel set up to a relay
Alert Aging:  30 minutes (have set this as low as 5 minutes and send without delay).
In each case, if I remove the condition of group, the notification is sent.
Why would this behavior occur?

Answer 1

Thanks Scott.  I've tried this both with the computer object and the health service watcher object.
What I'm doing is trying to create a dynamic group based on OU.  So, right now, the groups include the computer objects.  If I view group members, the group membership does populate ok with all of the machines from the targeted OU's for the dynamic
membership.
This is an example of the dynamic membership conditions I'm trying to create:
( ( Object is Windows Server AND ( Organizational Unit Equals OU=Test,OU=Servers,DC=domain,DC=local ) OR ( Organizational Unit Equals OU=Development,OU=Servers,DC=domain,DC=local) ) AND ( Object is Health Service Watcher AND ( Display Name Greater than empty
value ) AND True ) )
However, I'm noticing that the dynamic membership includes health service objects from all windows servers from all OU's and ignores the OU membership conditions.  But, I don't think that has anything to do with the failed notifications. 
I could be wrong.
I've also tried the following with the same problem:
( ( Object is Health Service Watcher AND ( Health Service Name Greater than empty value ) AND True ) AND ( Object is Windows Server AND ( Organizational Unit Equals OU=Test,OU=Servers,DC=domain,DC=local ) OR ( Organizational Unit Equals OU=Development,OU=Servers,DC=domain,DC=local
Both of the above groups populate both the computer and health service objects when viewing the members of the group with the problem being it adds all health server objects instead of limiting it to the OU's specified.
So, that lead me to a dynamic group membership of:
( Object is Windows Server AND ( Organizational Unit Equals OU=Test,OU=Servers,DC=domain,DC=local ) OR ( Organizational Unit Equals OU=Development,OU=Servers,DC=domain,DC=local ) )
This is what I have now (this morning) after adding the condition for the class. 
So, for the alert subscription rules, I added the group and the class and the monitor name:
Condition:  Raised by any instance in a specific group.  Checked, group name:  Test
Condition: Raised by any instance of a specific class:  Health Service Watcher
Condition:  created by specific rules or monitors.  checked, monitor:  "Computer Not Reachable"
Subscriber:  [email protected]
Channel:  smtp channel set up to a relay
Alert Aging:  30 minutes (have set this as low as 5 minutes and send without delay).
But, again if the group condition is present, the alert subscription doesn't work.
So, I suppose what I need to do is find a way to ensure I can build a group that includes health service objects from computer objects reside within specific OU's.  Perhaps I'm going about the dynamic membership conditions incorrectly?
Thanks
Ted