Actually, I have now figured out that invitations are actually sent once the Invite People (+) button is clicked at the bottom, but that I did not see the message that comes up on screen to say this, BUT more importantly, do these new invitees appear in the "Manage Pending Users" screen - when I click on that it simply says "All pending users have been activated".
How weird.
So the issue as I see it is that they do not appear in the Pending Users list...
Any ideas or is this me being stupid again?
Thanks all
Cliff