Hey ho everybody,

currently I developing a press center module.

For this I made a Settings page with currently 2 Options. The problem here is that every time I submit my form I get this :

An illegal choice has been detected. Please contact the site administrator.

<?php
function presscenter_settings_form($form, &$form_state) {

  // Define redirect path
  $form_state['cancel_return'] = 'admin/press';

  // Creating the Form


  $form['press_menu'] = array(
    '#type' => 'fieldset',
    '#title' => t('menu settings'),
    '#weight' => 5,
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  $form['press_menu'] += presscenter_settings_menu_select();

  
  $form['press_node'] = array(
    '#type' => 'fieldset',
    '#title' => t('node settings'),
    '#weight' => 5,
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  $form['press_node'] += presscenter_settings_node_select();
  
  
  // Form Actions
  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save configuration'),
  );

  $form['actions']['cancel'] = array(
    '#type' => 'submit',
    '#value' => t('Cancel'),
    '#submit' => array('callback_for_cancel_button'),
    '#limit_validation_errors' => array(),
  );

  return $form;
}

function presscenter_settings_form_submit($form, &$form_state){
  dsm($form_state);
}

/**
 * This function creates a select box with all menus on the current drupal 
 * install and returns it.
 */
function presscenter_settings_menu_select() {
  $options = array();

  $menus = menu_load_all();

  foreach ($menus as $key => $menu) {
    $options[$key] = $menu['title'];
  }

  $form['selection'] = array(
    '#type' => 'select',
    '#title' => t('Press menu'),
    '#options' => $options,
    '#description' => t('Select a press menu witch will be displayed on the press center page.'),
  );
  $form['enable'] = array(
    '#type' => 'checkbox',
    '#title' => t('Show menu on press Page.'),
    '#default_value' => TRUE,
  );

  return $form;
}


/**
 * This function creates a select box with all contenttypes on the current drupal 
 * install and returns it.
 */
function presscenter_settings_node_select() {
  $options = array();

  $content_types = node_type_get_names();
  
  foreach ($content_types as $key=>$type) {
    $options[$key] = $type;
  }

  $form['selection'] = array(
    '#type' => 'select',
    '#title' => t('Press contenttype'),
    '#options' => $options,
    '#description' => t('Select a press contenttype witch will be displayed on the press center page.'),
  );
  $form['enable'] = array(
    '#type' => 'checkbox',
    '#title' => t('Show nodes on press Page.'),
    '#default_value' => TRUE,
  );

  return $form;
}
?>

It was just a name problem