ImportError：Twisted需要zope.interface 3.6.0或更高版本：没有名为zope.interface的模块

Question

我正在尝试构建一个网络抓取工具（http://doc.scrapy.org/en/0.24/intro/tutorial.html#intro-tutorial），但是当我尝试启动抓取工具时，我收到此错误：

Traceback (most recent call last):
  File "/Applications/anaconda/bin/scrapy", line 7, in <module>
    from scrapy.cmdline import execute
  File "/Applications/anaconda/lib/python2.7/site-packages/scrapy/__init__.py", line 50, in <module>
    from twisted import version as _txv
  File "/Applications/anaconda/lib/python2.7/site-packages/twisted/__init__.py", line 53, in <module>
    _checkRequirements()
  File "/Applications/anaconda/lib/python2.7/site-packages/twisted/__init__.py", line 37, in _checkRequirements
    raise ImportError(required + ": no module named zope.interface.")
ImportError: Twisted requires zope.interface 3.6.0 or later: no module named zope.interface.

我用pip冻结检查了我的安装，似乎我安装了它：

zope.interface==4.1.1

这可能是什么问题？