我參考網路上PDO的做法，但在$stmt->execute();會一直出現
Warning: PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: parameter was not defined in D:\website\htdocs\google\111\test.php on line 9
的錯誤警告 我該如何修正他

<?
$connection = new PDO('mysql:host=localhost;dbname=444;charset=utf8', '444', '222');
$sql = "select 	member_real_name from member where member_id = :member_id";
$member_id = 29;
$stmt = $connection->prepare($sql);
$stmt->bindParam('i',$member_id);

   /* execute query */
   $stmt->execute();

   /* Store the result (to get properties) */
   $stmt->store_result();

   /* Get the number of rows */
   $num_of_rows = $stmt->num_rows;

   /* Bind the result to variables */
   $stmt->bind_result($member_id);
?>