我正在尝试使用pythonselenium登录到网页。我找到了一个元素并将其启用，但是当我尝试向其发送send_keys（）时出现错误。错误输出的主要内容（我认为）是

selenium.common.exceptions.ElementNotVisibleException: Message: Element is not currently visible and so may not be interacted with

我的代码是

from selenium import webdriver
from selenium.webdriver.common.keys import Keys
import contextlib

with contextlib.closing(webdriver.Firefox()) as driver:
    driver.get('http://www.etoro.com/au')
    elem = driver.find_element_by_class_name('inputUsername')
    print 'enabled:', elem.is_enabled()
    print 'selected:', elem.is_selected()
    elem.send_keys('myusername')

输出是

enabled: True
selected: False
Traceback (most recent call last):
  File "3_trying_again.py", line 10, in <module>
elem.send_keys('ianafterglow')
  File "/Users/ian/miniconda/lib/python2.7/site-packages/selenium/webdriver/remote/webelement.py", line 303, in send_keys
self._execute(Command.SEND_KEYS_TO_ELEMENT, {'value': typing})
  File "/Users/ian/miniconda/lib/python2.7/site-packages/selenium/webdriver/remote/webelement.py", line 385, in _execute
return self._parent.execute(command, params)
  File "/Users/ian/miniconda/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 173, in execute
self.error_handler.check_response(response)
  File "/Users/ian/miniconda/lib/python2.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 166, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.ElementNotVisibleException: Message: Element is not currently visible and so may not be interacted with
Stacktrace:
at fxdriver.preconditions.visible (file:///var/folders/5b/ym07nh6d74gcn_773ynwqkth0000gn/T/tmpN1MV8l/extensions/fxdriver@googlecode.com/components/command-processor.js:8959:12)
at DelayedCommand.prototype.checkPreconditions_ (file:///var/folders/5b/ym07nh6d74gcn_773ynwqkth0000gn/T/tmpN1MV8l/extensions/fxdriver@googlecode.com/components/command-processor.js:11618:15)
at DelayedCommand.prototype.executeInternal_/h (file:///var/folders/5b/ym07nh6d74gcn_773ynwqkth0000gn/T/tmpN1MV8l/extensions/fxdriver@googlecode.com/components/command-processor.js:11635:11)
at DelayedCommand.prototype.executeInternal_ (file:///var/folders/5b/ym07nh6d74gcn_773ynwqkth0000gn/T/tmpN1MV8l/extensions/fxdriver@googlecode.com/components/command-processor.js:11640:7)
at DelayedCommand.prototype.execute/< (file:///var/folders/5b/ym07nh6d74gcn_773ynwqkth0000gn/T/tmpN1MV8l/extensions/fxdriver@googlecode.com/components/command-processor.js:11582:5)

那么，我该怎么办？