Include Exclude not working

I've just purchased the extension bundle & include this in my theme folder
require get_template_directory() . '/meta-box-include-exclude/meta-box-include-exclude.php';

in the functions.php:

add_filter( 'rwmb_meta_boxes', 'prefix_include_exclude_demo' );
function prefix_include_exclude_demo( $meta_boxes )
{
	$prefix = 'pre_';
	$meta_boxes[] = array(
		'title'   => 'Include Metabox',
		'include' => array(
			// List of page templates. Can be array or comma separated. Optional.
			'template' => array( 'page-about.php' ),
		),
		'fields' => array(
			array(
				'name' => '',
				'id'   => 'about_options',
				'type' => 'text',
			),
		),
	);

	return $meta_boxes;
}

it doesn't seem to work on my page template that i've specified, can you guide me what's going wrong?

Thanks