Exhcnage Health Monitor isn't sending alerts

Exhcnage Health Monitor isn't sending alerts

It connects to my Exchange 2007 HUB server no problem and reports the correct number of items in the queues.  However, when either the warning or the critical threshold is reached, it doesn't send out an alert.  I know I've got the mail settings correct as I use them for other functions on the network.
 
Anyone seen this before and can point me in the right direction?
 
Thanks!