trouble writing to LDAP.... Undefined index: dn in /usr/local/horde/turba/lib/Driver/ldap.php on line 285

[Steve Neuharth]

  I've got turba working but I'd like to have the ability to add/modify
users in my LDAP source. I *THINK* I have everything set up right in
sources.php....

$cfgSources['localldap'] = array(
    'title' => 'LocalDirectory',
    'type' => 'ldap',
    'params' => array(
        'server' => '127.0.0.1',
        'port' => 389,
        'root' => 'dc=miniguys,dc=com',
        'bind_dn' => 'cn=Manager,dc=xxx,dc=com',
        'bind_password' => YOUWISH
    ),
    'map' => array(
        '__key' => 'dn',
        'name' => 'cn',
        'email' => 'mail',
        'homeAddress' => 'postaladdress',
        'homePhone' => 'homephone',
        'workAddress' => 'workaddress',
        'workPhone' => 'telephonenumber',
        'cellPhone' => 'mobile',
        'fax' => 'fax',
        'title' => 'title',
        'company' => 'company',
        'notes' => 'description'
    ),
    'public' => false,
    'readonly' => false
);

but I keep getting the error...

httpd: PHP Warning:  Undefined index:  dn in
/usr/local/horde/turba/lib/Driver/ldap.php on line 285

accompanied by a blank screen in the browser....

here is the code that generates the error... tho' I'm not sure how it's
supposed to work (that's why I'm asking)

   function makeKey($attributes)
    {
        $dn = '';
        if (is_array($this->params['dn'])) {
            foreach ($this->params['dn'] as $param) {
                if (isset($attributes[$param])) {
                    $dn .= $param . '=' . $attributes[$param] . ',';
                }
            }
        }

        $dn .= $this->params['root'];
        return $dn;
    }