iMessages not sending/receiving at all from OSX 10.8
I have Messages fully installed and my apple ID connected and verified in Mountain Lion. But anytime I try and send an iMessage to either an iMessage-enabled cell phone or their associated apple ID, it fails with the red ! icon.
Trying to send to my own apple ID from my iPhone also fails.
I have verified that all phones are on Wi-Fi, and the apple ID's being tested are properly set up to receive iMessages on the iPhones.
Any ideas? Both are iPhone 4S, one on AT&T and one on Verizon (though as I said, both are connected to wifi during the tests).
Macbook Pro, Mac OS X (10.6), 2.8 GHz Intel Core i7, 8 GB RAM





