It could just be bugged out for now, although I don't have enough information from this to help. But I know elite is having a number of issues right now as it is.
Try doing it again and then copy and pasting the error here.
wow, hmm yeah. Elite might be bugged out. If not, tomorrow just give activision a call. It will be pretty busy. But if worse comes to worse, you might be able to get one of them to get your invite sent.