#states in add node form How to use #states in add node form?
I don't experience any problems when use them with exposed filters (on user side), but cannot do the same when additing new nodes. 
I tried the following code:

function custom_module_form_alter(&amp;$form, $form_state, $form_id) {
  if ($form_id == 'article_node_form') {
    $form['field_coordinate']['und'][0]['#default_value'] = t('1');
    $form['field_name_tag']['und']['0']['#states'] = array(
      'invisible' =&gt; array('select[id="edit-field-location-tag-und"]' =&gt; array('value' =&gt; '1')),
    ); 
  };
}


Where is my mistake?
You need to set the state in the "value" key, so one level deeper as you tried.
E.g.:

$form['field_yourfieldname'][LANGUAGE_NONE][0]['value']['#states'] =
  array('visible' =&gt; 
    array('input[id="edit-field-otherfieldname"]' =&gt; array('checked' =&gt; TRUE))
  );