Show last post doesn't work!?

Hi. I thought what I wanted to do was simple but obviously, it’s not… I want to show the latest published post on my blog and I used this code:

<?php query_posts('posts_per_page=1'); ?>
<?php if (have_posts()) : while(have_posts()) : the_post(); ?>
<a>" rel="bookmark" title="Read: <?php the_title(); ?>"><?php the_title(); ?></a>
<?php the_excerpt(); ?>
<?php endwhile; ?>
<?php endif; ?>

If I don’t put a ‘tag=’ right after ‘posts_per_page=’ I have more than one post showing. I need to customize the latest post so I want to make a query for it. Is this a bug or else? There is no other query on my page. I don’t understand why it doesn’t work ??

Thanks for your help!