How can add flex relate field to subpanel

I have added a flex relate field to a subpanel using studio Parent TypeThe field parent_name does not populate with studio. But I have put below code :

'parent_name' => 

  array (
    'type' => 'parent',
    'studio' => 'visible',
    'vname' => 'LBL_PARENT',
    'link' => true,
    'sortable' => false,
    'ACLTag' => 'PARENT',
    'dynamic_module' => 'PARENT_TYPE',
    'id' => 'PARENT_ID',
    'related_fields' =>
    array (
      0 => 'parent_id',
      1 => 'parent_type',
    ),
    'width' => '10%',
    'default' => true,
    'widget_class' => 'SubPanelDetailViewLink',
    'target_module' => NULL,
    'target_record_key' => 'parent_id',
  ),But it did not populated with subpanel.

How can I fix this?
Thanks