insert data into a table with PDO

Question

Hello, I’m doing my first PDO code but when I am running the code, it brings me a mistake that I have no idea what it is, I appreciate the help from now.

<?php
session_start();
include('conn_prod.php');

$SendCadImg = filter_input(INPUT_POST, 'SendCadImg', FILTER_SANITIZE_STRING);
  if ($SendCadImg) {
    # code...
    $id_nec = filter_input(INPUT_POST, 'tema', FILTER_SANITIZE_STRING);
    $tema = filter_input(INPUT_POST, 'tema', FILTER_SANITIZE_STRING);
    $nome_img = $_FILES['arquivo']['name'];

    $result_img = "INSERT INTO necessaires (id_nec, tema, imagem, data) VALUES (:id_nec, :tema, :nome_img, NOW())";
    $insert_img = $conn_prod->prepare($result_img);
    $insert_img->bindParam(':id_nec', $id_nec);
    $insert_img->bindParam(':tema', $tema);
    $insert_img->bindParam(':imagem', $nome_img);

      $insert_img->execute();          

  } else {
      $_SESSION['img'] = "<p>Erro ao salvar oo dados</p>";
      header("Location: produtos.php");
  }
?>