Sharing screen with Messages.app on Mountain Lion Both computers are running OS X 10.8.4

When trying to initiate the screen sharing feature, the other computer gets the request, then clicks "Accept" but thats as far as we get.

Then we see this:


I have posted the contents of the "Details" section:

http://pastebin.com/raw.php?i=yWYYCbgv

I am thinking we may need to open some ports on the firewall. Anyone know which ports need to be open? Or if this is even the issue.
Try opening up port 5222 (for iChat/Messages).