Can anyone think of a reason why the Share Calendar menu item is not showing up on my zimbra install. Just recently upgraded to 3.1?

For all users, when right mouse clicking on the default calendar item, I only get Delete (grayed out), Edit Properties, Reload (grayed out).

I just went to check out the preview version and all worked there as expected.

No obvious messages in the logs (/var/log, /opt/zimbra/log)