Not responding javascript

<a onclick="wp_showhide.main(this, 'extra')" href="javascript:void(0)">
["Show More", "Hide More", "hidden"]
</a>
<div id="extra">
   extra
</div>

When I place that code, the entire [“Show More”, “Hide More”, “hidden”] shows up, including the <div> content. Am I missing a step somewhere?

http://wordpress.org/plugins/better-wordpress-showhide-elements/