Default preset for "Block title"

In some cases it would be convinient to set a default title for the block <none> or otherwise

I tried to modify nodeasblock_form_node_type_form_alter

  $form['nodeasblockset']['nodeasblock_default_title'] = array(
    '#type' => 'select',
    '#title' => t('Default block title'),
    '#default_value' => variable_get('nodeasblock_default_title_'. $node_type, 0),
    '#options' => array(
      0 => '<none>',
      1 => t('empty'),
    ),
  );

and

  $form['nodeasblockset']['nodeasblock_default_title'] = array(
    '#type' => 'textfield',
    '#title' => t('Default block title'),
    '#default_value' => variable_get('nodeasblock_default_title_'. $node_type, "<none>"),
  );

but even after clearing caches and all cache tables nothing extra would appear in the node type settings form
(admin/content/types/add)

any ideas ?