Your theme template is not able to load the following script in the footer area. In this case, you can manually add the following code in your theme's footer.php before BODY close,
Important - First of all see if there is a folder named JS in Wordpress-post-tabs folder on your server and then see if jquery.cookie.js is there. If it is not there then you can download latest version of WordPress Post Tabs plugin from Plugin directory and move that JS on your server.
It's unlikely not work. I've added code : <script src="http://www.thegreengadgets.com/wp-content/plugins/wordpress-post-tabs/js/jquery.cookie.js" type="text/javascript"></script> right before the body close, as you suggest. I've also checked folder wp-content/plugins/wordpress-post-tabs/js, and I found jquery.cookie.js in there.
But still it's only showing listed items there. What should I do now?