Doveadm auth test fails

I've been having trouble logging into my email server (postfix 3.4.13, dovecot 2.3.7.2, postfixadmin 3.3.8). I decided to try the doveadm auth test, and got the following result:

kwright@grace:~$ sudo doveadm auth test me@mydomain.com Password: passdb: me@mydomain.com auth failed extra fields: user=me@mydomain.com

I logged in to PostfixAdmin and made sure I was using the correct password, but got exactly the same result afterward. Should I have restarted Dovecot after changing the password? I'm totally confused by this problem; any and all suggestions will be gratefully received!

Ken