Trying to invite 3-star, Regular Member with 350+ posts & 19 Rep to the "Local SEO" Discussion Group (All interested are welcome to join, btw...) and I get the error message above (in title). Text of Member's named is typed exactly as it appears on posts. If I modify the spelling so that the 1st character is (incorrectly) lower-case, then the Member is "not found" so I assume 1) It is case specfic and 2) My spelling & case are correct, as a deliberate error causes it to fail in a different way. So I don't think it's the spelling input. However I WAS able to successfully accept the invitation of another member, so this it seems the problem is outbound (I cannot "invite"), but inbound (They ask to be accepted) seems to work. Hope this helps. Thanks for your efforts in advance.