Can't connect to IMAP

[HTF]

Hello,

I'm not able to connect to my IMAP server.

I can connect with mail client like Thunderbird etc. but roundcube just doesn't work.

The initial test after the installation was successful:

Connecting to ssl://mail.server.com...
IMAP connect:  OK(SORT capability: yes)

Logs:

IMAP Server

imap-login: Login: user=, method=PLAIN, rip=::ffff:xxx.xxx.xxx.xxx, lip=::ffff:xxx.xxx.xxx.xxx, TLS

Roundcube error log:

[06-Feb-2011 20:27:00 +0000]: IMAP Error: Login failed for an@email.com from xxx.xxx.xxx.xxx. AUTHENTICATE PLAIN: Authentication failed. in C:\webmail\program\include\rcube_imap.php on line 183 (POST /webmail/?_task=login&_action=login)

Roundcube IMAP log:

[06-Feb-2011 20:41:27 +0000]: S: * OK Dovecot ready.
[06-Feb-2011 20:41:27 +0000]: C: A0001 CAPABILITY
[06-Feb-2011 20:41:27 +0000]: S: * CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS AUTH=PLAIN
[06-Feb-2011 20:41:27 +0000]: S: A0001 OK Capability completed.
[06-Feb-2011 20:41:27 +0000]: C: A0002 AUTHENTICATE PLAIN aW5mb0BkYXJrc3BhY2UuY28AaW5mb0BkYXJrc3BhY2UuY28AUzNiYXN0MWFu
[06-Feb-2011 20:41:29 +0000]: S: A0002 NO Authentication failed.
[06-Feb-2011 20:41:29 +0000]: C: A0003 LOGIN an@email.com password
[06-Feb-2011 20:41:31 +0000]: S: A0003 NO Authentication failed.
[06-Feb-2011 20:41:31 +0000]: C: A0004 LOGOUT
[06-Feb-2011 20:41:31 +0000]: S: * BYE Logging out
[06-Feb-2011 20:41:31 +0000]: S: A0004 OK Logout completed.