求助关于Web服务引用出现问题

[WF-soft©]

web.GetFileList是获得FTP文件列表
web.Download是下载文件
两个方法都有登录FTP和关闭FTP的操作

Download方法放本地的时候没有问题，放到web.Download就引发未处理SoapException异常
这两个方法同时调用web服务是不是有什么漏洞或者冲突

        
public void DownDir(string FilePath, string FtpPath)
        {
            WF_web.WF_WebService web = new WF_web.WF_WebService();
            var fileList = web.GetFileList(FtpPath);
            
            if (fileList != null)
            {

                ThreadPool.QueueUserWorkItem((obj) =>
                {
                foreach (string file in fileList)
                {
                    if (file.Contains("<DIR>")) //if this is a dir need recursion download  
                    {
                        string[] temp = file.Trim().Split(new string[] { "<DIR>" }, StringSplitOptions.None);
                        string downloadDir = FilePath + "\\" + temp[1].Trim();
                        if (!Directory.Exists(downloadDir))
                        {
                            Directory.CreateDirectory(downloadDir);
                        }
                        DownDir(FilePath + "\\" + temp[1].Trim(), FtpPath + "/" + temp[1].Trim());
                    }
                    else
                    {
                        progressBarValue += 1;
                        string temp = file;
                        temp = new System.Text.RegularExpressions.Regex("[\\s]+").Replace(temp, " ");
                        var tempp = temp.Trim().Split(new string[] { " " }, StringSplitOptions.None);
                        string filename = tempp[tempp.Length - 1];
                        //此web.Download处发生异常
                        web.Download(FilePath + "\\", FtpPath + "/", filename);
                        Action<ListBox, String> updateAction = new Action<ListBox, String>(Settxt);
                        listBox.Dispatcher.BeginInvoke(updateAction, listBox, filename);
                        pb.Dispatcher.BeginInvoke(new ProgressBarSetter(SetProgressBar), progressBarValue);
                    }
                }
                }, null);
                if ((int)progressBarValue == (int)FileNum)
                {
                    listBox.Items.Insert(0, "更新完成----------------------");
                    MessageBox.Show("更新完成");
                }
            }
        }