Forum Can't invite users to Social Group
 

Greetings all. I'm stumped on something that I think is probably trivial, but for the life of my I can not figure out what's up.

I have a couple of users that can not be invited into Social Groups. The error that is given is " This user is not allowed to join Groups". I had hoped that there was some privacy setting they had turned on. Yet I can't find anything about the user that would prevent them from being invited. Could anyone offer any advice on what might be the cause?