When you create or register an account we ask for your email address. This email is then linked to your listing and profile. If your email address does not match what we have in our system already, you can receive this message.
For example, Gmail addresses allow users to add a "." in the address to filter messages. Emailaddress@gmail.com and Email.firstname.lastname@example.org belong to the same person as far as Gmail is concerned, but are two different email addresses. Please be sure to use the enter the same email address in the field.
You can use your email address to find your username.