Twilio自动回复器不发送短信

尝试启动并运行默认的自动应答器代码。我把它托管在heroku上，没有任何问题，我可以发短信给这个号码，显然，twilio号码确实收到了短信，但我自己的私人手机没有收到任何回复。

<?php
    require __DIR__ . '/vendor/autoload.php';
    use Twilio'Rest'Client;
    $sid='A...'; //blocked out the token
    $token='6....'; //blocked out the token
    $twilioNum='+1...'; //blocked out the number 

    $client = new Twilio'Rest'Client($sid, $token);
    function index(){
    $response = new Twilio'Twiml();
       $response->sms("Reply with one of the following keywords: monkey, dog, pigeon, owl.");
       echo $response;
    } 
    function monkey(){ 
       $response = new Twilio'Twiml();
        $response->sms("Monkey. A small to medium-sized primate that typically has a long tail, most kinds of which live in trees in tropical countries.");         
        echo $response;
    } 
    function dog(){
        $response = new Twilio'Twiml();
        $response->sms("Dog. A domesticated carnivorous mammal that typically has a long snout, an acute sense of smell, and a barking, howling, or whining voice."); 
        echo $response;
    } 

    $body = $_REQUEST['Body'];
    $result = preg_replace("/[^A-Za-z0-9]/u", " ", $body); 
    $result = trim($result); 
    $result = strtolower($result);
    if(stripos($body, "monkey") !== FALSE) {
        monkey();
    } else if(stripos($body, "dog") !== FALSE) {
        dog();
    } else if(stripos($body, "hello") !== FALSE) {
        index();
    }
    ?>

当我向twilio号码发送"monkey"时，我得到一个警告12200模式验证警告。以下是检查器中关于错误的内容:

<?xml version="1.0" encoding="UTF-8"?>
<Response><Sms>Monkey. A small to medium-sized primate that typically has a long tail, most kinds of which live in trees in tropical countries.</Sms>    </Response>

告诉我它收到了文本，知道我发送了那个关键字。但是re: the TwiML，这是我的TwiML Bin的相同格式——它被分配给那个消息服务。