[Plugin: OptionTree] radio image inside list item

hello;

i have a list-item id=”wm_contents_feature” with array, in this array i have a radio-image id=”icon” but i can’t change the icons of the radio image! i did the following code and try to put the list-item id in it & the radio-image id too, but nothing happen!

function filter_radio_images( $array, $field_id ) {

  if ( $field_id == 'icon' ) {
    $array = array(
      array(
        'value'   => 'left-sidebar',
        'label'   => __( 'Left Sidebar', 'option-tree' ),
        'src'     => OT_URL . '/assets/images/layout/one.png'
      ),
      array(
        'value'   => 'right-sidebar',
        'label'   => __( 'Right Sidebar', 'option-tree' ),
        'src'     => OT_URL . '/assets/images/layout/two.png'
      )
    );
  }

  return $array;

}
add_filter( 'ot_radio_images', 'filter_radio_images', 10, 2 );

array(
        'id'          => 'wm_contents_feature',
        'label'       => 'Feature Boxes',
        'desc'        => 'somethis to say!',
        'std'         => '',
        'type'        => 'list-item',
        'section'     => 'contents',
		'choices'     => array(),
		'settings'    => array(
          array(
            'id'      => 'icon',
            'label'   => 'Icon',
            'desc'    => 'somethis to say!',
            'std'     => 'None',
            'type'    => 'radio-image',
            'class'   => '',
            'choices' => array()
          ),
		)
      ),

http://wordpress.org/extend/plugins/option-tree/