我试图在查询的div内显示缩略图，但缩略图在div外，我不知道我做错了什么，下面是我的代码：

<?php
// WP_Query arguments
$args = array(
    \'post__in\' => array(26844,26829),
    \'post_type\'              => array( \'wedstrijd\' ),
    \'post_status\'            => array( \'published\' ),
);

// The Query
$shquery = new WP_Query( $args );

// The Loop
if ( $shquery->have_posts() ) {
    while ( $shquery->have_posts() ) {
        $shquery->the_post();
        echo \'<div class="wed_thumb">\' . the_post_thumbnail(\'et-pb-post-main-image\') . \'</div>\';
    }
} else {
    // no posts found
}

// Restore original Post Data
wp_reset_postdata();
?>