Issue with sorting by post date and custom post type

Question

I'm having a strange issue with sorting by post date.

I created a slideshow post type and it does by default order by post date but If I change the date posted through the admin the order doesn't update in the query, but it does get updated in the admin.

The Post Type

/* Slideshow Post Type */
add_action('init', 'slide_init');
function slide_init() {
    $labels = array(
        'name' => _x('Slides', 'post type general name'),
        'singular_name' => _x('Slide', 'post type singular name'),
        'add_new' => _x('Add New', 'slide'),
        'add_new_item' => __('Add New Slide'),
        'edit_item' => __('Edit Slide'),
        'new_item' => __('New Slide'),
        'view_item' => __('View Slide'),
        'search_items' => __('Search Slides'),
        'not_found' => __('No slides found'),
        'not_found_in_trash' => __('No slides found in Trash'), 
        'parent_item_colon' => '',
        'menu_name' => 'Homepage Slides'
    );
    $args = array(
        'labels' => $labels,
        'public' => true,
        'publicly_queryable' => true,
        'show_ui' => true, 
        'show_in_menu' => true, 
        'query_var' => true,
        'rewrite' => true,
        'capability_type' => 'post',
        'has_archive' => true, 
        'hierarchical' => false,
        'menu_position' => null,
        'supports' => array('title', 'editor', 'thumbnail')
    ); 
    register_post_type('slide', $args);
}

The Query

// Slideshow Query
$slideshow_args = array(
    'post_type' => 'slide',
    'posts_per_page' => '10',
);
$slideshow = new WP_Query( $slideshow_args );

Edit - -

I found out this has something to do with this line of code.

$slideshow_post_count = $slideshow->post_count; 

<?php if ($slideshow_post_count > 1) : ?>
<div class="controls span6">
    <span class="next"></span>
    <span class="pause"></span>
    <span class="prev"></span>
</div>
<?php endif; ?>

Answer 1

Have you played with the other arguments available to WP_Query?

$slideshow_args = array(
    'post_type' => 'slide',
    'posts_per_page' => '10',
    'orderby'        => 'post_date',
    'order'          => 'DESC'
);
$slideshow = new WP_Query( $slideshow_args );