Category Pagination

I’m using the following code:

<?php $paged = (get_query_var('paged')) ? get_query_var('paged') : 1; ?>
<?php query_posts('posts_per_page=2&cat=4'); ?>
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div class="tutorial">
<div class="image"></div>
<div class="text">
<h3><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h3>
<?php the_content(); ?>
</div>
<div class="cboth"></div>
</div>
<?php endwhile; endif; ?>
<?php if(function_exists('wp_pagenavi')) { wp_pagenavi(); } ?>

And whilst it generates the pagination, when one clicks on the pagination links, the index.php template is loaded – and therefore page 2 of the results isn’t shown at all.