need help with comments-post page asap

I created a custom template – I was able to add comments before but now I cannot.

and it sounds like you didnt do it properly. compare your single.php to the single.php that comes with the 2 themes that are included with wordpress.

Here’s what I have for single.php – seems to have what’s needed:

<?php get_header(); ?>
<?php get_sidebar(); ?>

<div class="single_post">
	<?php if(have_posts()) : while(have_posts()) : the_post(); ?>

		<div id="page_title"><?php the_title(); ?></div>

		<div class="single_entry">
			<em>Article posted on <?php the_time('l, F, jS, Y'); ?> at <?php the_time(); ?></em>
			<?php the_content(); ?>
			<?php the_tags(); ?>
			<div class="promote">
			<div id="page_title">Enjoy This Article?</div>
			<p>Subscribe to our <a href="<?php bloginfo('rss2_url');?>">RSS Feed</a></p>
			</div>
            <?php if ( comments_open() && pings_open() ) {
							// Both Comments and Pings are open ?>
							You can <a href="#respond">leave a response</a>, or <a href="<?php trackback_url(); ?>" rel="trackback">trackback</a> from your own site.

						<?php } elseif ( !comments_open() && pings_open() ) {
							// Only Pings are Open ?>
							Responses are currently closed, but you can <a href="<?php trackback_url(); ?> " rel="trackback">trackback</a> from your own site.

						<?php } elseif ( comments_open() && !pings_open() ) {
							// Comments are open, Pings are not ?>
							You can skip to the end and leave a response. Pinging is currently not allowed.

						<?php } elseif ( !comments_open() && !pings_open() ) {
							// Neither Comments, nor Pings are open ?>
							Both comments and pings are currently closed.

						<?php } edit_post_link('Edit this entry','','.'); ?>
            <?php comments_template();?>
		</div>

		<?php endwhile; else: ?>
		<h3>Sorry but we could not find what you were looking for</h3>
		<div><?php get_search_form(); ?></div>
		<?php endif; ?>
</div>
<?php include(TEMPLATEPATH . '/footer.php');?>

lets start here: how many theme files do you have? and what are they named?

take all of those files, and compare them to the corresponding files in the defualt theme.

if you need to doublecheck the neccessity of this — change to the default theme. does the problem go away?

The files I have are:
comments-popup.php
comments.php
footer.php
forum_post_page.php
functions.php
header.php
index.php
page.php
screenshot.jpg
sidebar.php
single.php
style.css

yes, the problem goes away if I change the theme.