Category loop showing "everything"??

I have a category ID 13 that is a subcategory of ID 9… however, when you go to the category even on the default template, ALL posts are showing up on the page… whether they’re 13, 9, or 33, 27, 3, etc…. i even tried making a custom “category-[catname].php” file and doing a custom loop like this

$mvids=get_posts(
     array("category" => 13,
           "post_status"=>"publish",
           "post_type" => "post")
     );
foreach( $mvids as $post ) :	setup_postdata($post);

and it STILLL is returning ALL posts….

PLEASE HELP