JFBinvite error

In the JFBCInvite configuration, there's a setting for "Invite Button Text". From the error your posting above, it sounds like that parameter is left blank. The text there is used the invitation button, so something needs to be there. A good starting point is the name of your site, so the button will look something like "Send 'You Site' Invitations"

Hope that helps,
Alex

Great to hear you got it going. Should you need anything else, just let us know!
Alex