Post create date in showthread

[vacancy33]

How can i show post create date in showthread template?

$post[postdate] is not work :/ Work for only postbit or postbit_legacy

I have a schema code;

<script type="application/ld+json">
{
    "@context":"http://schema.org",
    "@type":"DiscussionForumPosting",
    "@id":"********",
    "headline":"$thread[prefix_plain_html] $thread[title]<if condition='$pagenumber>1'> - <phrase 1='$pagenumber'>$vbphrase[page_x]</phrase></if>",
    "articleSection":"$foruminfo[title_clean]",
    "author":{"@type":"Person","name":"$thread[postusername]"},
    "datePublished":"$post[postdate]", [B]// this is not work in showthread template[/B]
    "dateModified":"",
    "image":"********************",
    "interactionStatistic":{
        "@type":"InteractionCounter",
        "interactionType":"https://schema.org/ReplyAction",
        "userInteractionCount":"$thread[replycount]"},
    "publisher":{
        "@type":"Organization",
        "name":"***********",
        "url":"**********",
        "logo":{"@type":"ImageObject",
        "url":"*******************"}
    },
    "mainEntityOfPage":{
        "@type":"WebPage",
        "@id":"***********"}
    }
</script>