此处这是消息：\n $ message。< =看到点了吗？

Here "Here is the message:\n $message". <= see the dot? That's supposed to be a semi-colon.

那是OP的代码无法正常工作的原因。

That, is the reason why OP's code is not working.

将 错误报告 添加到您的文件将有助于发现错误。

Add error reporting to the top of your file(s) which will help find errors, which it would have.

<?php 
error_reporting(E_ALL);
ini_set('display_errors', 1);

// rest of your code

侧注：错误报告仅应在登台中进行，而绝不能在生产中进行。

Sidenote: Error reporting should only be done in staging, and never production.