textarea type not working as expected

Hi,

I’m trying to add a textarea with a WYSIWYG editor as a meta box. I read the documentation and apparently setting the metabox type to “textarea” should already render a WYSIWYG editor, but that’s not the case for me. I get a simple textarea instead.

Can someone let me know what am I missing? I’m sure I must be missing something since this is a basic feature.

Thanks!

Here’s my code for the metabox:

add_action( 'admin_init', 'lu_portfolio_meta_boxes' );

function lu_portfolio_meta_boxes() {
  $lu_portfolio_description = array(
    'id'        => 'lu_portfolio_description',
    'title'     => __('Work Description', 'lumen'),
    'desc'      => __('Write a description for this work. Leave this field empty if you don\'t want to show the description area.', 'lumen'),
    'pages'     => array( 'portfolio' ),
    'context'   => 'normal',
    'priority'  => 'default',
    'fields'    => array(
      array(
        'id'          => 'lu_portfolio_description',
        'label'       => 'Work Description',
        'type'        => 'textarea'
      )
    )
  );
  ot_register_meta_box( $lu_portfolio_description );
}

http://ww.wp.xz.cn/extend/plugins/option-tree/