I use Rackspace for email and calendar. I obtained a URL for the Rackspace calendar, which I was able to use in Zimbra to see my calendar.

However, I cannot add or modify events. When I double-click an existing event, I do not see any editing options (as if it is in read-only mode). When I try to add an event, it gets automatically added to the default local calendar account (there is no option to pick between the default calendar and the external calendar).

Is this the normal behavior? Or am I doing something wrong?