sounds like you have it working, the other phones it is not picking up, go make a call from each of them that lasts at least a minute, and see if they are being stored, and you can search for them. Maybe the other phones are not making calls? The swith is usually set to send the packet update every 5 seconds, but that is a configurable setting on the "change sys ip" page, right below where you setup the IP address for the VMM.
I find if it works, it always works. Have you tried stopping, then restarting the SNMP service, or rebooting?
Mitch
AVAYA Certified Specialist