[horde] Horde Passwd module is not properly configured

[Admin Beckspaced]

Hello Horde Users ;)

I have installed the Horde 5.2.12 with Passwd module 5.0.5 and defined a 
SQL backend in backends.local.php (see below)
I have also setup a conf.php (see below)

But whenever I try to change a password I do receive the error:

'Passwd module is not properly configured'

How do I fix / debug this issue?

any help is more than appreciated ;)

Thanks & greetings
Becki

backends.local.php

$backends['sql'] = array(
     'disabled' => false,
     'name' => 'SQL Backend',
     'driver' => 'Sql',
     'policy' => array(
         'minLength' => 12,
         'maxLength' => 20,
         'maxSpace' => 0,
         'minUpper' => 1,
         'minLower' => 1,
         'minNumeric' => 1,
         'minSymbols' => 0,
     ),
     'params' => array(
         'phptype' => 'mysql',
         'hostspec' => 'localhost',
         'username' => 'dbuname',
         'password' => 'dbsecretpass',
         'encryption' => 'plain',
         'database' => 'somedb',
         'table' => 'some_users',
         'user_col' => 'userid',
         'pass_col' => 'passwd',
         'show_encryption' => false,
         // The following two settings allow you to specify custom 
queries for
         // lookup and modify functions if special functions need to be
         // performed.  In places where a username or a password needs to be
         // used, refer to this placeholder reference:
         //    %d -> gets substituted with the domain
         //    %u -> gets substituted with the user
         //    %U -> gets substituted with the user without a domain part
         //    %p -> gets substituted with the plaintext password
         //    %e -> gets substituted with the encrypted password
         //
         // 'query_lookup' => 'SELECT user_pass FROM horde_users WHERE 
user_uid = %u',
         // 'query_modify' => 'UPDATE horde_users SET user_pass = %e 
WHERE user_uid = %u',

     ),
);

conf.php

<?php
/* CONFIG START. DO NOT CHANGE ANYTHING IN OR AFTER THIS LINE. */
// $Id: afef93e939103554c1ec47b6cb4ae47e8ed5145b $
$conf['backend']['backend_list'] = 'hidden';
$conf['user']['change'] = false;
$conf['user']['refused'] = array('root', 'bin', 'daemon', 'adm', 'lp', 
'shutdown', 'halt', 'uucp', 'ftp', 'anonymous', 'nobody', 'httpd', 
'operator', 'guest', 'diginext', 'bind', 'cyrus', 'courier', 'games', 
'kmem', 'mailnull', 'man', 'mysql', 'news', 'postfix', 'sshd', 'tty', 
'www');
$conf['password']['strengthtests'] = false;
/* CONFIG END. DO NOT CHANGE ANYTHING IN OR BEFORE THIS LINE. */


test.php?app=passwd reports all is fine:

Passwd Version

     H5 (5.0.5)

PHP Version

     View phpinfo() screen
     View loaded extensions
     PHP Version: 5.5.14
     PHP Major Version: 5.5
     PHP Minor Version: 14
     PHP Version Classification: release
     You are running a supported version of PHP.

PHP Module Capabilities

     Ctype Support: Yes
     LDAP Support: Yes
     Mcrypt Support: Yes
     SOAP Support: Yes

Required Configuration Files

     config/backends.php: Yes
     config/backends.local.php: Yes
     config/conf.php: Yes

PHP Sessions

     Session counter: 1 [refresh the page to increment the counter]
     To unregister the session: click here

PEAR

     PEAR Search Path (PHP's include_path): 
/srv/ssl/webmail/httpdocs/lib:/srv/ssl/webmail/httpdocs/lib:.:/usr/share/php5/PEAR:/usr/share/php5
     PEAR: Yes
     Crypt_CHAP: Yes