Doveadm auth test fails

[Ken Wright]

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