I use the following for multiple post types, just replace foo
and bar
with your own post types:
$args = array(
'post_type' => array( 'foo', 'bar' ),
'orderby' => 'post_date',
// other parameters as needed
);
$q = new WP_Query( $args );
if ($q->have_posts()) : while ($q->have_posts()) : $q->the_post();
// do stuff
endwhile;
endif;