what is wrong with this code
class MyClass {

    private $db;

    // Constructor
    function __construct() {
        $this->db = new mysqli('localhost', 'root', 'root', 'Test_db');
        $this->db->autocommit(FALSE);
    }

    // Destructor
    function __destruct() {
        $this->db->close();
    }

    // Main method
    function MyFun() {

        // Check for required parameters
        if (isset($_POST["name"]) && isset($_POST["username"]) && isset($_POST["password"]) && isset($_POST["email"])) {
        echo "Before n";
        $name = $_POST["name"];
        $username = $_POST["username"];
        $password = $_POST["password"];
        $email = $_POST["email"];
        $activation = 0;
        echo "After n";
            // tracking
            $stmt = $this->db->prepare("INSERT INTO users (name, username, password, email,activation) VALUES (?, ?, ?, ?, ?)");
            $stmt->bind_param("is", $name, $username, $password, $email, $activation); //Line 95
            $stmt->execute();
            $stmt->close();

        }

[15-Apr-2011 15:09:10] PHP Warning:  mysqli_stmt::bind_param() [<a href='function.mysqli-stmt-bind-param'>function.mysqli-stmt-bind-param</a>]: Number of elements in type definition string doesn't match number of bind variables in /Applications/MAMP/htdocs/Test/reg.php on line 95

$stmt->bind_param("is", $name, $username, $password, $email, $activation);

$stmt->bind_param("sssss", $name, $username, $password, $email, $activation);

$stmt->bind_param("is", $name, $username, $password, $email, $activation);

$stmt = $this->db->prepare("INSERT INTO users (name, username, password, email,activation) VALUES (?, ?, ?, ?, ?)");
$stmt->bind_param($name, $username, $password, $email, $activation);

$stmt = $this->db->prepare("INSERT INTO users (**is**, name, username, password, email,activation) VALUES (?, ?, ?, ?, ?)");
$stmt->bind_param("**is**", $name, $username, $password, $email, $activation);