PHP预处理语句执行过程中不知道什么有关问题，求大神解答，分数不多，下面是代码

PHP预处理语句执行过程中不知道什么问题，求大神解答，分数不多，下面是代码

<br>$servername = 'servername'; //服务器名称<br>$username = 'username'; //数据库用户名<br>$password = 'password'; //登录密码<br>$dbname = 'mydb';<br><br>//创建连接<br>$conn = new mysqli($servername, $username, $password, $dbname);<br><br>//检测连接(PHP 5.2.9和5.3.0版本适用)<br>/* if($conn->connect_error){<br>
die('连接失败：' . $conn->connect_error);<br>} */<br><br>//检测连接(兼容更早版本)<br>if(mysqli_connect_error()){<br>
die('连接失败:' . mysqli_connect_error());<br>}<br>else{<br>
$sql = "INSERT INTO myguests VALUES(?, ?, ?)";<br>
<br>
//为mysqli_stmt_prepare()初始化statement对象<br>
$stmt = mysqli_stmt_init($conn); <br>
echo $stmt; //不知道为什么$stmt是空的，没有数据<br>
<br>
//预处理语句<br>
if(mysqli_stmt_prepare($stmt, $sql)){<br>
//绑定参数<br>
mysqli_stmt_bind_param($stmt, 'sss', $firstname, $lastname, $email);<br>
<br>
//设置参数并执行<br>
$firstname = 'Sam';<br>
$lastname = 'Poly';<br>
$email = [email protected]';<br>
mysqli_stmt_execute($stmt);<br>
<br>
$firstname = 'Mary';<br>
$lastname = 'Moe';<br>
$email = [email protected]';<br>
mysqli_stmt_execute($stmt);<br>
<br>
$firstname = 'Julie';<br>
$lastname = 'Dooley';<br>
$email = [email protected]';<br>
mysqli_stmt_execute($stmt);<br>
<br>
echo '插入成功';<br>
}<br>}<br>

好像mysqli_stmt_init($conn)执行后没反应，我echo了一下，没东西输出，所以后面的mysqli_stmt_prepare($stmt, $sql)也执行不下去了，实在不清楚为什么没有执行，也没有报错
------解决思路----------------------
你用混了！
$conn = mysqli_connect(....)
mysqli_stmt_init($conn)
这是一对

$conn = new mysqli(.....)
$conn ->stmt_init()
这才是一对