2.3.7-cvs: pgsql.php error

[Claus Heiko Niesen]

I'm trying to install IMP with postgresql support but since I added the 
configuration I get the following error:

Warning: Undefined index: protocol in /usr/local/lib/php/DB/pgsql.php on 
line 95

The weird part is that the preferences are actually stored and I can 
continue using IMP by reloading the page.

I have the following lines in horde/config/horde.php:

$conf['prefs']['driver'] = 'sql';
$conf['prefs']['params'] = array();
$conf['prefs']['params']['phptype'] = 'pgsql';
$conf['prefs']['params']['hostspec'] = 'localhost';
$conf['prefs']['params']['username'] = 'horde';
$conf['prefs']['params']['password'] = 'secret';
$conf['prefs']['params']['database'] = 'horde';
$conf['prefs']['params']['table'] = 'horde_prefs';

and the table layout is as follows:

horde=# \d horde_prefs
                Table "horde_prefs"
  Attribute  |     Type      |      Modifier
------------+---------------+---------------------
  uid        | character(32) | not null
  scope      | character(16) | not null default ''
  pref_name  | character(32) | not null
  pref_value | text          |
Index: horde_prefs_pkey

horde=# \d horde_prefs_pkey
  Index "horde_prefs_pkey"
  Attribute |     Type
-----------+---------------
  uid       | character(32)
  scope     | character(16)
  pref_name | character(32)
unique btree (primary key)

I did the test with doing a "su" to the webserver uid and accessing the 
database by doing
"psql -h localhost -U www -W horde".  Everything works fine, select, 
insert, update, and delete.  I haven't found anything interesting in the 
logs of apache or postgresql.  Does anybody have an idea of what I 
configured wrong?
   Claus