Why wp_query display posts form another category?

I use this function:

<?php 

        $args = array(
        'posts_per_page' => 6,
        'category' => 317,
        'orderby' => 'most_recent'
        );

        $the_query = new WP_Query( $args );

        ?>

Problem is it displays 4 posts from category “317” and 2 from another category. Why? I would like to have posts only form 317 category. (Now in this category there is 4 posts).