Forgot password - user unknown

I created an account in the forum and forgot the password. Now when I click “forgot password” and put in the mailadress it says user with this mailadress unknown. What can I do?

You should be able to see your registered email address in Preferences under your Profile.

yes i see the mailadress. But when I put it in “forgot password” and then click it says this mailadress is not known…