Sheet Set Manager missing?

Hi,

Yesterday I could bring up the Sheet Set Manager (Ctrl-4). Running in a trial version (original hard drive died and I rebuilt - but everything was working)

I reactivated after help from support, but today I cannot get the Sheet Set manager to launch.

Entering SHEETSET in Command Window, I see the command in the selection list, but then I get 'Unrecognized command SHEETSET'.

It's obviously something I have done, but no clue as to where to look.

Any Ideas?