I invited a friend a couple weeks ago and he signed up

But now when he tries to sign in he gets an error "email isn't registered. "

His username is "pickmaster"

Any suggestions?

Thanks

I will send you the email he is registered with in PM so that you can double check it with him.

He must have made a typo when he inserted the email or something similar. Account exists, the email is correct. A password recovery request was sent to his email.