If I understand you correctly, someone shared you a form, but you didn't receive the email. If it's the case, can you please check your junk mail folder to see if this email is filtered out as junk mails?
The email is correct!
I've looked in the SPAM folder and did not get the invitation for account activation.
De: Wenlan_Du email@example.com
Enviada em: segunda-feira, 8 de julho de 2013 06:37
Re: Link for Co-Authors
Can you ask the author to un-share the form with you and add you again as a co-author?