Not able to start Script.

[Kubunter]

So far the needed Files are where they should be.
But when starting the Script I get following error:
Python Library Module 'DuetWebAPI.py' is required. Obtain from https://github.com/DanalEstes/DuetWebAPI Place in same directory as script, or in Python libpath.
I have placed the DuetWebAPI.py in the DuetLapse folder and additional in the python libpath, but without success.

How can this error be solved?