一个关于json_decode()后显示为空的有关问题

header("Content-type:text/html;charset=utf-8");
$url = "http://218.22.201.163/wic/api.php/early_warning/xcyjservice/U/administrator/P/wic/jw/118.589036,30.055954";
       $postUrl = str_replace(' ', '%20', $url);
	   $param = '';
        $curlPost = $param;
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $postUrl);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $curlPost);
        curl_setopt($ch, CURLOPT_TIMEOUT, 60);
        $data = curl_exec($ch);
	
        curl_close($ch);
        //var_dump($data);die;//
        var_dump(json_decode($data, true));