Sidebar Code Help

Hello All,
I have looked over the following code many times, and can’t find what I’m missing to allow each sidebar to operate independently. The code below is from my about page. The problem is every page is still loading the main default sidebar, the widgets in the About sidebar area are not showing up. Any help spotting the coding error causing the problem would be great!

sidebar-about.php

<div id="rightsidebar">

	<div id="widgets-wrap-sidebar">

     <?php
      if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('about-sidebar') ) :
      endif; ?>

    </div>    

</div><!-- rightsidebar end -->

About Page Template

<?php get_header(); ?>

<div id="contentwrap">

<div id="leftcontent">

		<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

		<?php the_content(); ?>

		<?php edit_post_link('Edit this entry.', '<p>', '</p>'); ?>

		<?php endwhile; endif; ?>

</div><!-- leftcontent -->

<?php get_sidebar('about-sidebar'); ?>

</div><!-- contentwrap -->

<?php get_footer(); ?>

Functions Code

// Custom Sidebars
			if ( function_exists('register_sidebar') ) {
		register_sidebar(array(
		'before_widget' => '<div id="%1$s" class="widget-sidebar %2$s">',
		'after_widget' => '</div>',
		'before_title' => '<h3 class="widget-title">',
		'after_title' => '</h3 class="widget-title">',
		));
		}
		if ( function_exists('register_sidebar') ) {
		register_sidebar(array(
		'name' => 'Homepage Sidebar',
		'id' => 'homepage-sidebar',
		'description' => 'Homepage Sidebar',
		'before_widget' => '<div id="%1$s" class="widget-sidebar %2$s">',
		'after_widget' => '</div>',
		'before_title' => '<h3 class="widget-title">',
		'after_title' => '</h3 class="widget-title">',
		));
		}

		register_sidebar(array(
		'name' => 'About Sidebar',
		'id' => 'about-sidebar',
		'description' => 'About Sidebar',
		'before_widget' => '<div id="%1$s" class="widget-sidebar %2$s">',
		'after_widget' => '</div>',
		'before_title' => '<h3 class="widget-title">',
		'after_title' => '</h3 class="widget-title">',
		));