如何修复此php参数mysqli错误？

如何解决如何修复此php参数mysqli错误？

我得到的错误是

“致命错误：未捕获错误：在C：\ xampp2 \ htdocs \ Website \ register.PHP：13中的bool上调用成员函数bind_param（）：13堆栈跟踪：＃0 {main}抛出于C：\ xampp2 \ htdocs \ Website \ register.PHP在第13行“

代码是

<?PHP
    $email = $_POST['email'];
    $password = $_POST['password'];
    $username = $_POST['uname'];

    // Database connection
    $conn = new MysqLi('localhost','root','','website');
    if($conn->connect_error){
        echo "$conn->connect_error";
        die("Connection Failed : ". $conn->connect_error);
    } else {
        $stmt = $conn->prepare("insert into website(user_name,password,email)values(?,?,?)");
        $stmt->bind_param("sss",$email,$password,$username);
        $execval = $stmt->execute();
        echo $execval;
        echo "Registration successfully...";
        $stmt->close();
        $conn->close();
    }
?>

有人能帮我吗，请让我困惑。