Почему не работает скрипт?

<?php

$extensions = array('jpeg', 'jpg', 'png', 'gif');
$max_size = 500000;
$path = 'avatars/';
$response = '';
if (isset($_POST))
{
    $ext = strtolower(pathinfo($_FILES['image']['name'], PATHINFO_EXTENSION));
      $path = $path . uniqid() . '.' . $ext;
 
      if (move_uploaded_file($_FILES['image']['tmp_name'], $path))
      {
        $response = "<img style='height: 200px;' src='$path'>";
      }
	  
}
 
 	  $a= "hi";
	  $class = "1";
	  $t_date = "INSERT INTO topicer VALUES ('','".$a."','".$a."','".$a."','".$class."','".$a."','".$response."')";
 
echo $t_date;


?>