大神帮忙看下是哪里错了，要怎么修复（急）！谢谢

请求结果（上边是发送的XML源原串，下方是返回结果），php代码在下方。

我把上方输出的XML源串拿去“支付接口签名校验工具”中测试，测试结果是“校验通过”

php代码

调用页面（做了自动加载）：

Pay::createOrder(1,1);

pay类部分代码如下：

<meta charset="utf-8">
<?php
class Pay{
	public static $appid="wx4********";
	protected static $secret="9d324e********18";
	
	public static $mch_id="*********";//商户号
	public static $api_key="a************";//APIkey
	
	protected static $siteurl="https://*************/wechat";//回执域名
	
	public static function createOrder($aid,$amount,$billno=''){
		date_default_timezone_set("PRC");
		$url="https://api.mch.weixin.qq.com/pay/unifiedorder";
		$data=self::getTem($aid,$amount,$billno);
		$result=self::httpRequest($url,$data);
		$re1 = simplexml_load_string($result,'SimpleXMLElement',LIBXML_NOCDATA);
		$re2 = json_encode($re1);
		$result2 = json_decode($re2,true);
		echo htmlspecialchars($data);
		echo "<br/>";
		print_r($result2);
		//return $result2;
	}
	
	public static function getTem($aid,$amount,$billno){
		$data = self::getSign($aid,$amount,$billno);
		$str="<xml>";
		foreach($data as $key => $value){
			if(is_numeric($value)){
				$str.="<".$key.">".$value."</".$key.">";
			} else {
				$str.="<".$key."><![CDATA[".$value."]]></".$key.">";
			}
		}
		$str.="</xml>";
		return $str;
	}
	
	public static function getSign($aid,$amount,$billno){
		$data=array();
		$data['appid'] = self::$appid;//应用ID
		$data['body'] = "付费文档获取-支付";//商品描述
		$data['mch_id'] = self::$mch_id;//直连商户号
		$data['nonce_str'] = self::getStr(12);//随机字符串
		$data['notify_url'] = self::$siteurl ."/info.php";//通知地址
		$data['out_trade_no'] = $billno==''?time().rand(10000,99999):$billno;//商户订单号
		$data['trade_type'] = "NATIVE";//交易类型
		$data['total_fee'] = $amount;//标价金额
		$data['attach']= $aid;//
		
		ksort($data);
		$str = self::getString($data);
		$str .= "key=". self::$api_key;
		$sign = strtoupper(MD5($str));
		$data['sign'] = $sign;//签名
		return $data;
	}
	
	public static function getString($data){
		$str="";
		foreach($data as $k=>$v){
			$str.=$k."=".$v."&";
		}
		return $str;
	}
	
	public static function getStr($number){//随机字符串$number长度
		$name=substr(md5(uniqid(microtime(true),true)),8,$number);
		return $name;
	}
	
	public static function httpRequest($url,$data=''){
		$curl = curl_init();
		curl_setopt($curl,CURLOPT_URL, $url);
		curl_setopt($curl,CURLOPT_SSL_VERIFYPEER,FALSE);
		curl_setopt($curl,CURLOPT_SSL_VERIFYHOST,FALSE);
		if(!empty($data)){
			curl_setopt($curl,CURLOPT_POST,TRUE);
			curl_setopt($curl,CURLOPT_POSTFIELDS,$data);
		}
		curl_setopt($curl,CURLOPT_HEADER,FALSE);
		curl_setopt($curl,CURLOPT_RETURNTRANSFER,TRUE);
		$output = curl_exec($curl);
		curl_close($curl);
		return $output;
	}


	
}