Impossible to install cgkit package in PyCharm

Hello,

I'm using latest version of PyCharm with Python.

When I try to add 'cgkit' to my Project Interpreter, installation fails: 

error occurred: Non-zero exit code (1)

Command output: Collecting cgkit. Could not find a version that satisfies the requirement cgkit (from versions: )
No matching distribution found for cgkit

Does somebody know how I can solve this problem managing to install cgkit package?

Thanks for your help,

Davide Bassano