Python Twisted does not work on Eclipse -

I've twisted Python and I'm trying to create a simple server on Eclipse and I'm getting the following error:

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importError: a module named zope.interface

I'm not sure how to fix it. Have not installed all the dependencies already?

Be sure that you:

1. PyDev has installed
2. Turn / install zope.interface and in your PYTHONPATH.
3. Configured your eclipse project as a Python / Pydev project.
4. The interpreter in the Eclipse Environment (Pydev Settings) is configured.