My loop appears to be broken

So I’m trying to create a loop on a page template but the very same loop I use on my main blog page doesn’t work on a page template.

can someone tell me what I’m doing wrong?

<?php
/*
Template Name: Blog_Template
*/
?>

<?php get_header(); ?> <!-- gets header.php. open html, wrapper div open. header div closed -->

<div id="container">
	<?php if(have_posts()) : ?>
		<?php while(have_posts()) : the_post(); ?>  <!-- Begining of "The Loop" -->

			 <!-- If the post is in the category 4 (News), we simply pass to the next post. -->
			<?php if (in_category('3')) continue; ?>

			<div class="post" id="post-<?php the_ID(); ?>"> <!-- Start of Each Post -->
				<h2><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a></h2> <!-- Title for Posts -->
				<div class="entry">
					<?php the_content(); ?>
					<p class="postmetadata"> <!-- Metadata for posts (Category, comments author etc) -->
						<?php _e('Categories:'); ?> <?php the_category(', ') ?> <?php _e('by'); ?> <?php  the_author(); ?><br />
						<?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?> <?php edit_post_link('Edit', ' | ', ''); ?>
					</p>
				</div>
			</div>
		<?php endwhile; ?>
		<div class="navigation"> <?php posts_nav_link("|","<<","&#187"); ?> </div> <!-- posts_nav_link('in between','before','after') -->
	<?php else: ?>
		<div class="post">
			<h2><?php _e('Not Found'); ?></h2> <!-- only displays if no posts are found -->
		</div>
	<?php endif; ?>
</div>

<?php get_sidebar(); ?> <!-- gets sidebar.php completely closed. -->

<?php get_footer(); ?> <!-- gets footer.php div wrapper closed also closes html and body -->