I've just upgraded to Kubuntu Trusty. There were some errors during the update which I did not understand, so I just plowed on and restarted. Now I can't get multiple desktops. More precisely, the "Workspace Behavior" section of System Settings does not include the Virtual Desktops section at all. I assume I'm missing some module or other -- but which one?
SnapOverflow
you have to go into appearance and click on the "enable workspaces" checkbox. hope it helps