[imp] Login always return login failed

[GB]

After a fresh clean install of horde webmail 1.2.2 login always return the
same message in /tmp/horde.log : 

Mar 22 18:59:08 HORDE [error] [imp] FAILED LOGIN for gilles [192.168.xx.yy]
to {127.0.0.1:143 [imap/notls]} [pid 27541 on line 139 of
"/var/www/horde/imp/lib/Auth/imp.php"] 

I follow the horde install guide (web site and readme file). 



The test http://your-server/horde/test.php is ok. 

The imap test is ok, and I can connect to imap server with telnet and other
clients (thunderbird and webmail). 

Database and tables are created and user horde can connect. 

I've allready read dozens of mails and try some changes (see below) but
nothing helps me. 



In config/conf.php I've tryied 

$conf['auth']['admins'] = array('gilles'); ('gilles' is a valid imap user
and can connect with telnet and others mail clients) 

$conf['cookie']['domain'] = ''; 

$conf['session']['use_only_cookies'] = both true and false. 

$conf['auth']['checkip'] = both true and false. 



imp/config/servers.php 

$servers['imap'] = array(
 'name' => 'IMAP Server',
 'server' => '127.0.0.1',
 'protocol' => 'imap/notls',
 'port' => 143,
); 



Regards

Gilles