PHP微信开发 回复功能总是不行

<?php
namespace Home\Controller;
use Think\Controller;
class IndexController extends Controller {
public function index(){
//1.获取到微信推送过来post数据(xml格式)
$postArr=$GLOBALS['HTTP_RAW_POST_DATA'];
//2.处理消息类型，并设置回复类型和内容
$postObj=simplexml_load_string($postArr,'SimpleXMLElement',LIBXML_NOCDATA);

//回复用户消息
$toUser =$postObj->FromUserName;
$fromUser =$postObj->toUserName;
$time =time();
$msgType ='text';
$content ='闪现送人头';
$template ="<xml>
<ToUserName><![CDATA[%s]]></ToUserName>
<FromUserName><![CDATA[%s]]></FromUserName>
<CreateTime>%s</CreateTime>
<MsgType><![CDATA[%s]]></MsgType>
<Content><![CDATA[%s]]></Content>
</xml> ";
$info =sprintf($template,$toUser,$fromUser,$time,$msgType,$content);
echo $info;
}
}