用XDocument.Parse读取ftp中的xml文件时出错

using System;
using System.IO;
using System.Net;

class Program
{
    static void Main()
    {
        string ftpUrl = "ftp://example.com/xmlfile.xml";
        string ftpUsername = "username";
        string ftpPassword = "password";

        try
        {
            // 创建FTP请求
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpUrl);
            request.Method = WebRequestMethods.Ftp.DownloadFile;
            request.Credentials = new NetworkCredential(ftpUsername, ftpPassword);

            // 发送FTP请求并获取响应
            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            {
                // 读取FTP响应流
                using (Stream stream = response.GetResponseStream())
                {
                    // 将FTP响应流转换为XML文档
                    using (StreamReader reader = new StreamReader(stream))
                    {
                        string xmlContent = reader.ReadToEnd();
                        // 使用XDocument.Parse解析XML文档
                        XDocument xmlDocument = XDocument.Parse(xmlContent);

                        // 在这里可以对XML文档进行进一步处理
                        // ...

                        // 输出XML文档的根元素名称
                        Console.WriteLine("Root element: " + xmlDocument.Root.Name);
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }
    }
}