Problems with query post with specific tag

i allways use the same code
but for some reason, now its not working

when a user go to a category, it shows the latest post, but, i want that one post stays as “featured” using a simple tag
so i make a query with that tag, and i have:

<div class="category-last">
                <?php $recent = new WP_Query("showposts=1&tag=featured"); while($recent->have_posts()) : $recent->the_post();?>
                <div class="thumb"><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_post_thumbnail( array(303,160) ); ?></a></div>
                <div class="title"><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></div>
                <div class="excerpt"><?php wp_limit_post(200,'...',true); ?></div>
                <div class="read"><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>">Leer Nota</a></div>
        <div class="comments"><?php comments_popup_link(__('Sin Comentarios',woothemes), __('1 Comentario',woothemes), __('% Comentarios',woothemes)); ?></div>
                <?php endwhile; ?>
                </div>

any idea why is not working?