无法使用ftputil下载文件

Question

我正在尝试下载过去6天内创建的文件，我可以打印文件的名称，但不能将文件从FTP服务器下载到本地系统。请说明我错在哪里。

import ftplib
import ftputil
import os
import datetime

now=datetime.datetime.now()
print (now)
ago=now-datetime.timedelta(days=6)
print (ago)

class MySession(ftplib.FTP):
    def __init__(self, host, userid, password, port):
        ftplib.FTP.__init__(self)
        self.connect(host, port)
        self.login(userid, password)
ftp = ftputil.FTPHost('host', 'user', 'pwd', port=21,
                     session_factory=MySession)


dir_dest=os.chdir('C:/Python34/New folder')

for root,dirs,files in ftp.walk('Windows Triage' , topdown=True):
    for name in files:
        path=ftp.path.join(root,name)
        st=ftp.stat(path)
        ctime=datetime.datetime.fromtimestamp(st.st_mtime)
        if ctime>ago:
            print(name)
            for fname in name:
                fpath = ftp.path.join(root,fname)
                if ftp.path.isfile(fpath):
                    ftp.download(fpath,os.path.join(dir_dest, fname), 'b')