Autobahn cannot import name error

I have installed twisted and Autobahn websocket by using ``` pip install twisted pip install autobahn ``` But when I import any of the factories from Autobahn, I get the cannot import name error. ``` >>> from twisted.internet import reactor >>> from autobahn.websocket import WebSocketClientFactory Traceback (most recent call last): File "<console>", line 1, in <module> ImportError: cannot import name WebSocketClientFactory ``` Is there anything I am missing? Here's the pip freeze ``` Twisted==13.2.0 Twisted-Core==12.3.0 Twisted-Names==12.3.0 Twisted-Web==12.3.0 autobahn==0.7.4 websocket==0.2.1 websocket-client==0.13.0 ```