[Plugin: Tabbed Widgets] No Invisible Sidebar

Hi WordPressers

I’m having a bizarre issue with the Tabbed Widgets plugin on WordPress 3.2.1 and Automattic’s Toolbox theme.

The “Invisible Sidebar” is not showing up under Appearance>Widgets

This appears to be a theme issue. Under my previous theme and Twenty-Ten, “Invisible Sidebar” is displayed.

Under my new theme and Twenty-Eleven, it is not displayed.

The only theme prerequisites I’ve been able to find relate to unique identifiers for the frontend sidebars, which I have:

register_sidebar( array (
		'name' => __( 'Sidebar 1', 'toolbox' ),
		'id' => 'sidebar-1',
		'before_widget' => '<aside id="%1$s" class="widget %2$s">',
		'after_widget' => "</aside>",
		'before_title' => '<h1 class="widget-title">',
		'after_title' => '</h1>',
	) );

I’d appreciate any ideas why “Invisible Sidebar” is not appearing in the WordPress admin panel for some themes.

Has anyone else encountered this?

Thanks for your ideas….