I'm pretty sure it's something they turn "on" and "off". They send out invites in batches and there aren't any available at the moment? Feel free to correct me if I've misunderstood.
yea, my guess would be that the invites work while the game is open.. Seems to make sense... i know the entire time the game was open last it was "on", Probably because that would blow to get an invite and not be able to play LOL
I have a question too. I had 5 invites. there were two friends on the list. I sent an invite to each. I got in but the other invite was not delivered. I tried several times. I contacted my friend to see if she had any known problem such as an address change but she knew of none. Why didn't her invite go through? Both invites were done at the same time while the game was open.