zen settings options don't apear anywhere

function zen_settings($saved_settings, $subtheme_defaults = array()) {

Actualy this should display a form with various options ... But WHERE ? I don't see it anywhere in theme configuration

And in zen-classix, beside mannually adding zen-fixed.css in theme-settings.php, where it is suposed to be the web page configuration with this form :

$form = array();
$form['zen_classic_fixed'] = array(
'#type' => 'checkbox',
'#title' => t('Use fixed width for theme'),
'#default_value' => $settings['zen_classic_fixed'],
'#description' => t('The theme should be centered and fixed at 960 pixels wide.'),
);