Problems Adding App Engine to Google Apps Domains

We have added domains to our application without any problems in the last couple of months, following these instructions https://developers.google.com/appengine/articles/domains

Since yesterday, we were not able to click "Activate this service", we get this error message "An error occurred while trying to install this application. Please try again later."

We also tried this with old domains and with different applications and got the same error, so the problem seems to be more common and not isolated from specific domains / applications.

Does anyone know how to solve this?

Thanks Ron