使用Python-Selenium自动执行GMAIL登录

我正在尝试使用Python的Selenium软件包自动登录到GMail。但是，我无法完成任务并得到以下错误：

Traceback (most recent call last):
  File "C:\Users\Surojit\Desktop\Python\automaticpasswordFiller.py", line   21, in <module>
    passwordElem = browser.find_element_by_id('Passwd')
  File "C:\Users\Surojit\AppData\Local\Programs\Python\Python35-32\lib\site- packages\selenium\webdriver\remote\webdriver.py", line 266, in  find_element_by_id
    return self.find_element(by=By.ID, value=id_)
  File "C:\Users\Surojit\AppData\Local\Programs\Python\Python35-32\lib\site- packages\selenium\webdriver\remote\webdriver.py", line 744, in find_element
    {'using': by, 'value': value})['value']
  File "C:\Users\Surojit\AppData\Local\Programs\Python\Python35-32\lib\site-  packages\selenium\webdriver\remote\webdriver.py", line 233, in execute
    self.error_handler.check_response(response)
  File "C:\Users\Surojit\AppData\Local\Programs\Python\Python35-32\lib\site- packages\selenium\webdriver\remote\errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.NoSuchElementException: Message: Unable to locate  element: {"method":"id","selector":"Passwd"}
Stacktrace:
    at FirefoxDriver.prototype.findElementInternal_   (file:///C:/Users/Surojit/AppData/Local/Temp/tmpceecsm46/extensions/fxdriver@goo glecode.com/components/driver-component.js:10770)
     at FirefoxDriver.prototype.findElement   (file:///C:/Users/Surojit/AppData/Local/Temp/tmpceecsm46/extensions/fxdriver@goo  glecode.com/components/driver-component.js:10779)
    at DelayedCommand.prototype.executeInternal_/h   (file:///C:/Users/Surojit/AppData/Local/Temp/tmpceecsm46/extensions/fxdriver@goo    glecode.com/components/command-processor.js:12661)
    at DelayedCommand.prototype.executeInternal_    (file:///C:/Users/Surojit/AppData/Local/Temp/tmpceecsm46/extensions/fxdriver@goo glecode.com/components/command-processor.js:12666)
    at DelayedCommand.prototype.execute/<   (file:///C:/Users/Surojit/AppData/Local/Temp/tmpceecsm46/extensions/[email protected]/components/command-processor.js:12608) 

我写的简单代码是：

from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.common.by import By
import time

browser = webdriver.Firefox()
browser.get('http://gmail.com')
action = webdriver.ActionChains(browser)
emailElem = browser.find_element_by_id('Email')
emailElem.send_keys("MyUserName")
browser.find_element_by_name('signIn').click()
#browser.get('https://accounts.google.com/ServiceLogin?         service=mail&continue=https://mail.google.com/mail/#password')
passwordElem = browser.find_element_by_id('Passwd')
passwordElem.send_keys("MyPassword")
browser.find_element_by_name('signIn').click()

另外，我尝试通过将代码与以下类似问题的答案进行比较来找出代码中的错误：使用Python Selenium自动连接我的Gmail帐户

有人可以引导我走上正确的道路，让我知道我在哪里犯错吗？

PS：这是我关于stackoverflow的第一篇文章。请原谅我在发布问题时犯的任何错误