If you have more than one Facebook account (hey, some people do X_X) you could try the other account. To be honest, I'm not sure what changed to make the EU page work and give me a key, but I did have to close the site and reopen it, login and log out from facebook, and keep trying the keycode page many times before it did finally work. I was using Firefox, but I doubt the browser has anything to do with it.
The US page definitely will not work yet, because Dionaea has announced that herself and the team is working to resolve the issue. Because of that, the offer will be available on the US page longer so that it can be sorted out and the codes properly distributed. (
http://forum.us.runesofmagic.com/showthr…0839#post560839)
As for codes that are "invalid," that's probably a separate issue altogether. I was lucky enough that I didn't have that problem. Maybe if a screenshot is taken of that error, you can get a new code emailed to you or something?