[SA-exim] authenticator failed

[sam wun]

Hi list,

I m running Exim4 in FreeBSD 5.3 Stable.
Authentication is via pam_pwdfile.

Login cyrus_imap is successful, but fail to send authenticated email.
The error in exim/mainlog file is as follow:

2005-03-04 12:44:21 plain authenticator failed for ([192.168.1.214]) [220.22.137.56]: 535 Incorrect authentication data (set_id=me at home.com)
2005-03-04 12:44:22 login authenticator failed for ([192.168.1.214]) [220.22.137.56]: 535 Incorrect authentication data (set_id=me at home.com)

The following is the authentication defined in the exim/configure file:
plain:
driver = plaintext
public_name = PLAIN
server_condition = "${if pam{$2:$3}{1}{0}}"
server_set_id = $2

login:
driver = plaintext
public_name = LOGIN
server_prompts = "Username:: : Password::"
server_condition = "${if pam{$1:$2}{1}{0}}"
server_set_id = $1

login id and password is written in imap.passwd file:
me at home.com:$1$4T7FJPbP$acsTSqwUDog9VXfJ9vuGB0

its permission is:
# ls -l /usr/local/etc/imap.passwd
-rw-r--r--  1 cyrus  cyrus  150 Mar  4 11:05 /usr/local/etc/imap.passwd

Is there a way I can debug where the problem is? 
and how to fix this issue? 
It is also noted that I can't even send email from the local network.

Thanks
Sam