Editing a loop to bring in one category type.

Evening all.

Hope this is the right place to post this but I need a little help. I have the following code which brings in a list of portfolios, and places them on a page in a grid format. At present the code brings in all the portfolio types (of which there are 3, divided into different categories). Is there a way I can edit the code so that I can bring in just one category type?

I have tried the following:

<?php query_posts( array( 'post_type' => 'myportfoliotype', 'category_name' => 'news','paged' => $paged, 'posts_per_page' => 12));

		if ( have_posts() ) : while ( have_posts() ) : the_post();?>

but it displays a blank page.

If I remove:

', 'category_name' => 'news'

it returns a page will all the categories listed.

I would be greatful if anyone could help.

Many thanks

The full code is:

<?php
/*
Template Name: Modular Gallery
*/
?>
<?php get_header(); ?>

<div class="container container_alt">
Modular Gallery
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

<div id="folio-wrap">

	<ul id="portfolio-list" class="centerrow"> 

        <?php query_posts( array( 'post_type' => 'myportfoliotype', 'category_name' => 'news','paged' => $paged, 'posts_per_page' => 12));

		if ( have_posts() ) : while ( have_posts() ) : the_post();?>

            <?php
				$large_image =  wp_get_attachment_image_src( get_post_thumbnail_id(get_the_ID()), 'fullsize', false, '' );
				$large_image = $large_image[0];
				$another_image_1 = get_post_meta($post->ID, 'themnific_image_1_url', true);
				$video_input = get_post_meta($post->ID, 'themnific_video_url', true);
            ?>

            <li id="post-<?php the_ID(); ?>" class="centerfourcol item_full">

                <span class="imgwrap">

                    <?php the_post_thumbnail('folio',array('title' => "")); ?>

                    <a class="hoverstuff-zoom" rel="prettyPhoto[gallery]" href="<?php if($video_input) echo $video_input; else echo $large_image; ?>"><i class="icon-zoom-in"></i></a>
                    <a class="hoverstuff-link" href="<?php the_permalink(); ?>"><i class="icon-link"></i></a>

                </span>	

                <div style="clear:both"></div>

                <h3><a href="<?php the_permalink(); ?>"><?php echo short_title('...', 6); ?></a></h3>

                <?php echo themnific_excerpt( get_the_excerpt(), '290'); ?>

            </li><!-- #post-<?php the_ID(); ?> -->

		<?php endwhile; endif; ?> 

   </ul>	

        <div class="clear"></div>

		<div class="pagination"><?php pagination('?', '?'); ?></div>

	<?php wp_reset_query(); ?>

</div>

</div>

<?php get_footer(); ?>