Macbook Pro and iPad cannot log onto iMessage: "Could not sign into iMessage. An error occurred during activation. Try Again"

I logged out of iMessage on my Macbook Pro (OS X Yosemite) and when I tried to log back in I got an error message saying that apple "Could not sign in to iMessage: An error occurred during activation. Try again." I did the first four steps that apple recommends but that has not worked. Does any one have any suggestions? I logged out and logged back on on my iPhone 6 and everything works perfectly. My mac and iPhone both have the latest software updates.

Thanks.