[imp] php error?

[Andre Grove]

hello there

i have installed the following packages on a Redhat 7.3 machine:

horde-2.2.3-1.noarch.rpm    php-imap-4.2.2-0horde3.i386.rpm
imp-3.2.1-1.noarch.rpm      php-mysql-4.2.2-0horde3.i386.rpm
php-4.2.2-0horde3.i386.rpm  turba-1.2-1.noarch.rpm

my problem is that when i go to http://server/horde/imp, i get the 
following error:

Notice: Use of undefined constant SORTARRIVAL - assumed 'SORTARRIVAL' in 
/var/www/html/horde/imp/config/prefs.php on line 503

Notice: Use of undefined constant SORTARRIVAL - assumed 'SORTARRIVAL' in 
/var/www/html/horde/imp/config/prefs.php on line 507

Notice: Use of undefined constant SORTDATE - assumed 'SORTDATE' in 
/var/www/html/horde/imp/config/prefs.php on line 508

Notice: Use of undefined constant SORTFROM - assumed 'SORTFROM' in 
/var/www/html/horde/imp/config/prefs.php on line 509

Notice: Use of undefined constant SORTSUBJECT - assumed 'SORTSUBJECT' in 
/var/www/html/horde/imp/config/prefs.php on line 510

Notice: Use of undefined constant SORTSIZE - assumed 'SORTSIZE' in 
/var/www/html/horde/imp/config/prefs.php on line 511

Warning: Cannot add header information - headers already sent by (output 
started at /var/www/html/horde/imp/config/prefs.php:503) in 
/var/www/html/horde/imp/lib/base.php on line 76

is this a php error? an how do i solve it?

Thanks

Andre