Previous Post link does not work

Hello,

I am having trouble getting my previous post link to work at the bottom of my home page (TruthLighthouse.com). My theme originally did not have a previous post link so I started working on trying to get one. For now, it has a simple link that takes them to the archives but I literally want it to go to the list of the previous posts. I read various topics on the subject and none seemed to work. I tried editing the index.php with the following code – <?php next_posts_link('Older Entries »', 0); ?><?php previous_posts_link('« Newer Entries', 0) ?> and at first, it seems to be working. It produces a previous post link at the bottom. If I click it, however, it simply reproduces the same page. It does not list the older posts. Below is the code I currently have.

<!-- Middle Column -->
		<div id="midcolumn">
			<h2>Recent Posts</h2>
			<!-- Loop for latest news -->
			<?php $oddentry = 'class="gray" '; ?>
			<?php query_posts('cat=13,14,15,16,17,18,19,20,21,29,30,22,23,24,25,28,26,27&orderby=rand&showposts=10'); ?>
			<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
			<div <?php echo $oddentry; ?>>
				<div class="midcolumnpost">
					<h3><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h3>
					<?php the_excerpt('Read More', '<img><a>', 'content', false, 'More...', true);?>
					<div class="details">
						 | <a href="<?php echo get_permalink(); ?>" title="Read More">Read More</a>
					</div>
				</div>
			</div>
			<?php /* Changes every other post to a different class */	$oddentry = ( empty( $oddentry ) ) ? 'class="gray" ' : ''; ?>
			<!-- End of Loop for middle column -->
			<?php endwhile; else : ?>
			<?php endif; ?>
<center><b><u><a href="http://www.truthlighthouse.com/archives/">>>>Older Posts<<<</a></u></b></center>
		</div>
		<!-- /Middle Column -->

I tried the following code and got the results mentioned above.

<!-- Middle Column -->
		<div id="midcolumn">
			<h2>Recent Posts</h2>
			<!-- Loop for latest news -->
			<?php $oddentry = 'class="gray" '; ?>
			<?php query_posts('cat=13,14,15,16,17,18,19,20,21,29,30,22,23,24,25,28,26,27&orderby=rand&showposts=10'); ?>
			<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
			<div <?php echo $oddentry; ?>>
				<div class="midcolumnpost">
					<h3><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h3>
					<?php the_excerpt('Read More', '<img><a>', 'content', false, 'More...', true);?>
					<div class="details">
						 | <a href="<?php echo get_permalink(); ?>" title="Read More">Read More</a>
					</div>
				</div>
			</div>
			<?php /* Changes every other post to a different class */	$oddentry = ( empty( $oddentry ) ) ? 'class="gray" ' : ''; ?>
			<!-- End of Loop for middle column -->
			<?php endwhile; else : ?>
			<?php endif; ?>
<center><b><u><?php next_posts_link('Older Entries »', 0); ?><?php previous_posts_link('« Newer Entries', 0) ?></u></b></center>
		</div>
		<!-- /Middle Column -->

Any ideas why this will not show the actual previous posts?