[horde] horde/imp problem : can't login

[youri]

Hello,

i'm running a debian box with Horde: 2.2.4, IMP: 3.2.3 and Turba: 1.2.1
Im using courier-imap with maildir support, and a Mysql server.

At first i tested my configs :
on horde test.php everything looks ok, i don't doon't have ldap and 
postgresql support, but i don't need it.
On the imp test.php page i have made the php imap support test and got a 
good result.

For the config,

in horde.conf i have
$conf['auth']['driver'] = ''
so that imp do the authentication stuff.

and for the prefs:
$conf['prefs']['driver'] = 'sql';
$conf['prefs']['params'] = array();
$conf['prefs']['params']['phptype'] = 'mysql';
$conf['prefs']['params']['hostspec'] = 'localhost';
$conf['prefs']['params']['username'] = 'lions_horde';
$conf['prefs']['params']['password'] = '8zEaLQNh';
$conf['prefs']['params']['database'] = 'horde';
$conf['prefs']['params']['table'] = 'horde_prefs';

in IMP i have just changed the server.php to put my imap server like this :
$servers['imap'] = array(
     'name' => 'Lions Mail Server',
     'server' => 'localhost',
     'protocol' => 'imap/notls',
     'port' => 143,
     'folders' => '',
     'namespace' => '',
     'maildomain' => 'lions.lu',
     'smtphost' => 'localhost',
     'realm' => 'lions.lu',
     'preferred' => ''
);

the courier-imap server is configured to make it's authentication 
through MySQL, and it is working fine, i can get the message with a mail 
client and on localhost with telnet.

Now the problem :
When i try to login in IMP, the browser works, waiting for webmail to 
respond.
here is the only entry in the horde.log (in debug mode)
Jan 10 19:31:25 HORDE [info] [imp] clean session [on line 882 of 
"/var/www/argon7/lions/webmail/horde-2.2.4/lib/Horde.php"]

I can't see a connection on the database, the mysql.log don't log 
anything when trying to connect with IMP.


Can anybody give a idea?

thanks,

youri