wordpress add post image not showing

image not showing when i insert in wordpress add post but it will show on post description area

echo '<div id="droppable">';
$z =1;
foreach($list_images as $k=>$i){
    $meta = get_post_meta($post->ID,$i,true);
    $img = (isset($meta)) ? '<img src="'.wp_get_attachment_thumb_url($meta).'" width="100" height="100" alt="" draggable="false">' : '';
    echo '<div class="image-entry" draggable="true">';
    echo '<input type="hidden" name="'.$k.'" id="'.$k.'" class="id_img" data-num="'.$z.'" value="'.$meta.'">';
    echo '<div class="img-preview" data-num="'.$z.'">'.$img.'</div>';
    echo '<a href="javascript:void(0);" class="get-image button-secondary" data-num="'.$z.'">'._x('Add New','file').'</a><a href="javascript:void(0);" class="del-image button-secondary" data-num="'.$z.'">'.__('Delete').'</a>';
    echo '</div>';
    $z++;
}
echo '</div>';
?>

enter image description here