[horde] Horde does not log regardless my settings

[Jan Kořínek]

Hello all.

I must have overseen something, but I am not able to get at least a bit 
of standard PHP error log from horde. I read mayn guides, tried to set 
it up accordingly, but I did not succeed.

Horde: 3.1.3
Imp: 4.1.3
Apache: 2.0.56
PHP: 5.1.6.pl6

The horde configuration:
$conf['debug_level'] = E_ALL;
$conf['compress_pages'] = true;
$conf['umask'] = 07;
$conf['tmpdir'] = '/tmp/';
$conf['log']['priority'] = PEAR_LOG_ALL;
$conf['log']['ident'] = 'HORDE';
$conf['log']['params'] = array();
$conf['log']['name'] = '/tmp/horde.log';
$conf['log']['params']['append'] = true;
$conf['log']['type'] = 'file';
$conf['log']['enabled'] = true;
$conf['log_accesskeys'] = true;


PHP vhost configuration regarding logging:
display_errors	On
display_startup_errors	Off
error_log	syslog
error_reporting	2047
log_errors	On
log_errors_max_len	1024

vhost contains a clause:
ErrorLog /some/file

After apache restart, the file is created but does not contain anything.
The only file containing messages is /tmp/horde.log

The reason, why I need this log is, that after login to IMP I get only 
"zero size reply" and thats all. I'm desperate, because horde is our 
primary webmail and does not run for the last two days...

Thanks a lot for any hint.
Jan