Hey I got that same error now that I went back in there, so thank you for letting me know.
I will have to make an extra bonus for people who helped me with Mercury Retrograde shadow period glitches!
I didn't have FB on (since I stay off my account as much as possible, too) and that might have been a problem, so I put it back in there.
If you click RSVP, the tickets are free, so you just select the number of tickets, type in your 411 and you're done.
Et voila!
kk done!
Sa-weeeeeeet!