Change post template via url parameter

I needed to serve up the post content only.
Everything else, including the header, footer and the sidebars needed to be stripped out.
I needed this ‘post content only’ version to be always available, for every post, but for the original fully styled posts to be available as well.

And I found this!!
http://scratch99.com/wordpress/development/how-to-change-post-template-via-url-parameter/

I added the following code to my theme’s functions.php file:

function sjc_add_query_vars($vars) {
    return array('template') + $vars;
}
add_filter('query_vars', 'sjc_add_query_vars');

function sjc_template($template) {
  global $wp;
  if ($wp->query_vars['template']=='basic') {
    return dirname( __FILE__ ) . '/single-basic.php';
  }
  else {
    return $template;
  }
}
add_filter('single_template', 'sjc_template');

And I created a file called single-basic.php, then added the following code.

<div id="content">
    <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
          <h2 class="item"><span class="fn"><?php the_title(); ?></span></h2>
        <?php the_content(); ?>
    <?php endwhile; else: ?>
    <?php endif; ?>
</div>

But It didn’t work!
(http://domain.com/postname/?template=basic) is still blank page.
Please help me…