When I try to add a second email account to my Geary (version 0.8.3 on Ubuntu 15.04), the 'Add' button of the account dialogue window remains inactive. Despite having filled in all required fields. Any ideas?

Unfortunately, I have a localized version installed (German). Hence, I don't know the exact button names of the English form. However, you can see the button Hinzufuegen, which says 'Add'. This very button is not clickable but remains inactive.