libapache2-mod-auth-mysql wouldn't work on standard apache

[B@MB@M]

Binary package hint: libapache2-mod-auth-mysql

1.
# lsb_release -rd
Description: Ubuntu 9.04
Release: 9.04

2. (not installed anymore)
# apt-cache policy apache2
apache2:
  Installed: (none)
  Candidate: 2.2.11-2ubuntu2.2
  Version table:
     2.2.11-2ubuntu2.2 0
        500 http://nl.archive.ubuntu.com jaunty-updates/main Packages
        500 http://security.ubuntu.com jaunty-security/main Packages
     2.2.11-2ubuntu2 0
        500 http://nl.archive.ubuntu.com jaunty/main Packages

3 & 4
I've been using this package on all my systems, but just recently I tried it with the standard apache package. Normally, I use the "user per vhost" apache version, apache2-mpm-itk.

I had been trying to configure this package, and every time I listed the configuration in the vhost for a certain directory, it would go blank when browsing to it. Nothing in the error.log and 1 line in the access.log saying a 401 error. (but didn't appear in the browser).
<ip> - - [05/Aug/2009:09:38:15 +0200] "GET /admin HTTP/1.1" 401 401 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1" "-" 0 <fqdn>

I had put on the loglevel = debug, but the only it wasn't showing (in comparison to a working apache (the itk package)) was the query on the DB.
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1715): Handling an authentication request for section /home/www/nivo.nl/intranet
/public_html/administrator/
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1756): Starting basic user auth for [bart] in /home/www/nivo.nl/intranet/public_
html/administrator/, child pid 31276
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1543): No DB connection open - firing one up
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1289): Opening DB connection for /home/www/nivo.nl/intranet/public_html/administ
rator/
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1365): Persistent in /home/www/nivo.nl/intranet/public_html/administrator/ is 1
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1551): Correctly opened a new DB connection
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1571): Constructing password collection query with passfield=[passwd], table=[us
ers], userfield=[bart], where_clause=[]
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1409): sec->dbh in /home/www/nivo.nl/intranet/public_html/administrator/ is
[Tue Aug 04 13:45:27 2009] [debug] mod_auth_mysql.c(1416): Ordinary query

so, got a blank page without a query being executed.
After installing the itk package everything went fine.
# apt-cache policy apache2-mpm-itk
apache2-mpm-itk:
  Installed: 2.2.6-02-1build4.2
  Candidate: 2.2.6-02-1build4.2
  Version table:
 *** 2.2.6-02-1build4.2 0
        500 http://nl.archive.ubuntu.com jaunty-updates/universe Packages
        500 http://security.ubuntu.com jaunty-security/universe Packages
        100 /var/lib/dpkg/status
     2.2.6-02-1build4 0
        500 http://nl.archive.ubuntu.com jaunty/universe Packages

Config:
* part of vhost
  <Directory "/path/to/directory.nl/">
    Options Indexes FollowSymLinks MultiViews

    AuthBasicAuthoritative Off
    AuthUserFile /dev/null

    AuthMySQL On
    AuthName "<name>"
    AuthType Basic

    Auth_MySQL_DB mod-auth-mysql
    Auth_MySQL_Password_Table users
    Auth_MySQL_Group_Table users
    Auth_MySQL_Username_Field username
    Auth_MySQL_Password_Field passwd
    Auth_MySQL_Group_Field groups
    Auth_MySQL_Empty_Passwords Off
    Auth_MySQL_Encryption_Types Plaintext Crypt_DES PHP_MD5
    Auth_MySQL_Authoritative On

    require group admin
  </Directory>