非常简单的pip python-twitter问题;无法导入twitter

Sun Oct 14$pip install python-twitter
Requirement already satisfied (use --upgrade to upgrade): python-twitter in /Library/Python/2.7/site-packages
Requirement already satisfied (use --upgrade to upgrade): setuptools in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python (from python-twitter)
Requirement already satisfied (use --upgrade to upgrade): simplejson in /Library/Python/2.7/site-packages (from python-twitter)
Requirement already satisfied (use --upgrade to upgrade): oauth2 in /Library/Python/2.7/site-packages (from python-twitter)
Requirement already satisfied (use --upgrade to upgrade): httplib2 in /Library/Python/2.7/site-packages (from oauth2->python-twitter)
Cleaning up...
Sun Oct 14$python
Python 2.7.2 (default,Nov 17 2011,13:22:48) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.1.00)] on darwin
Type "help","copyright","credits" or "license" for more information.
>>> import twitter
Traceback (most recent call last):
  File "<stdin>",line 1,in <module>
ImportError: No module named twitter
>>>

我需要做一个virtualenv吗？还有什么可以继续？对不起,我缺乏理解,但任何帮助表示赞赏.

编辑#1
试图让tweepy工作但……可能在这里有两个版本的Python 2.7

Sun Oct 14$pip install --upgrade tweepy
Requirement already up-to-date: tweepy in ./tweepy-1.11-py2.7.egg
Cleaning up...
Sun Oct 14$python
Python 2.7.2 (default,"credits" or "license" for more information.
>>> import tweepy
Traceback (most recent call last):
  File "<stdin>",in <module>
ImportError: No module named tweepy
>>>

我想我可能安装了两个版本的Python 2.7;一个通过自制软件和Apple默认.自制软件安装是否可能将软件包放在/Library/Python/2.7/site-packages中？

再次,提前thx