http://test.dwagn.org/wagn/Matthias_Smith is an account request, and clicking the invite link fails because the key is "matthia_autratum" i'm guessing:

Can't find it!

Can't find this Account Request

404 Not Found

Changing the link by hand to http://www.wagn.org/account/accept?card[key]=matthia_autratum gets to the invite page with subject and message, but clicking "Invite" there gets the same message as above.