In ubuntu 11.10 I had problems adding my google calendar .
In gconf-editor, I found the evolution entry in apps/evolution
there is a key called “source” in addressbook and calendar also, and they differ. the calendar had no “google” source. I simply copied it from the addressbook part (double click on sources under addressbook, select the one with name=”Google”, press edit, copy it’s content) and added a new entry to the source key under calendar (same procedure, but press add when editing the key).
Got that from ubuntuforums.org
Thank you! I’ve been searching high and low on the Internet for a solution to this after a recent upgrade to Gnome 3. Now I have all my calendars back!