Posts not showing

I’m developing a web for a company and I’m having problems with the posts.
I have a index.php that shows only one post from one category, and a resumes.php page that should show the resumes for 30 people in the company. I introduce the resumes as posts with the category ‘resume’, so I try to select all the posts from this category and show them all in the resumes page. The problem is that this code works fine in index.php, but not in resumes.php:

<?php query_posts($query_string . ‘&cat=6’);?>
<?php if (have_posts()) :
while (have_posts()) :
the_post();
the_content();
endwhile;
endif; ?>
<?php wp_reset_query();?>

My idea is to show all the posts of the resumes category (ID=6) and, if possible, order them by title.
Also, I would like to be able to select from this posts by a tag, that is, show all the posts from the resumes category, that have ‘Finance’ or ‘IT’ or ‘Management’ as tags.

Any ideas? Why isn’t working the loop in the resumes page?

Thanks in advance,