Php PDOException:SQLSTATE[HY093]：无效参数编号：未定义参数

请帮我解决不了，试了三天却不知道是什么原因把这样的消息扔给了我。（以下是我的完整代码）

插入新员额
在此插入新帖子
职位名称：
文章作者：
张贴图片：
帖子内容：

上述表格用于在数据库中插入和提交数据

// PHP 

  <?php 
include("includes/connect.php");

if (isset($_POST['submit'])) {

    $title = $_POST['title'];
    $datenow = date('Y/m/d');
    $author = $_POST['author'];
    $content = $_POST['content'];
    $image_name = $_FILES['image_name']['name'];
    $image_type = $_FILES['image_name']['type'];
    $image_size = $_FILES['image_name']['size'];
    $image_tmp = $_FILES['image_name']['tmp_name'];

    if ($title =='' || $author =='' || $content =='') {
        echo "<script>alert('Any feild is empty')</script>";
        exit();
    }
    if ($image_type =='image/jpeg' || $image_type =='image/png' || $image_type =='image/gif') {

        if ($image_size<=5000000000) {
            move_uploaded_file($image_tmp, "images/$image_name");
        }
        else{
            echo "<script>alert('Image is larger, only 50kb size is allowed')        </script>";
        }
    }
    else{
        echo "<script>alert('image type is invalid')</script>";
    }

    // insert query
              $sth = $con->prepare(" INSERT INTO posts (post_title, post_date,   post_author, post_image, post_content) VALUE (:title,:datenow,:author,:image_name,:content) ");

    $sth->bindParam(':post_title', $title);
    $sth->bindParam(':post_date', $datenow);
    $sth->bindParam(':post_author', $author);
    $sth->bindParam(':post_image', $image_name);
    $sth->bindParam(':post_content', $content);

       $sth->execute();

 echo "<h1>Form Submited Successfully</h1>";

}

?>

   // $sth->execute(); is throwing error massage as above

//PHP
您绑定了错误的值。您没有绑定post_*值。见下文：

$sth = $con->prepare(" INSERT INTO posts (post_title, post_date, post_author, post_image, post_content) VALUES (:post_title,:post_date,:post_author,:post_image,:post_content) ");

$sth->bindParam(':post_title', $title);
$sth->bindParam(':post_date', $datenow);
$sth->bindParam(':post_author', $author);
$sth->bindParam(':post_image', $image_name);
$sth->bindParam(':post_content', $content);

您正在绑定
：title，：datenow，：author..
而不是
：post\u title，：post\u date..
谢谢。我很高兴能帮助您。
$sth = $con->prepare(" INSERT INTO posts (post_title, post_date, post_author, post_image, post_content) VALUES (:post_title,:post_date,:post_author,:post_image,:post_content) ");

$sth->bindParam(':post_title', $title);
$sth->bindParam(':post_date', $datenow);
$sth->bindParam(':post_author', $author);
$sth->bindParam(':post_image', $image_name);
$sth->bindParam(':post_content', $content);