gammaMotionAnalysis fails on windows 10

Hi,
I am running Psychopy 1.85.6 on windows 10. I just ran the gammaMotionNull.py demo and got 4 files (2 .psydat and 2 .tsv). I then launched the gammaMotionAnalysis.py script. When I select the 4 files, I get the following error:

Running: C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\demos\coder\experiment control\gammaMotionAnalysis.py

Traceback (most recent call last):
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\demos\coder\experiment control\gammaMotionAnalysis.py”, line 29, in
thisDat = fromFile(thisFileName)
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\tools\filetools.py”, line 35, in fromFile
contents = cPickle.load(f)
cPickle.UnpicklingError: invalid load key, ’
'.

I then tried to launch the .psydat only and got the following error:

Running: C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\demos\coder\experiment control\gammaMotionAnalysis.py

Traceback (most recent call last):
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\demos\coder\experiment control\gammaMotionAnalysis.py”, line 50, in
fit = data.FitWeibull(combinedInten, combinedResp, guess=guess, expectedMin=0.0)
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\data.py”, line 4614, in init
self._doFit()
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy\data.py”, line 4627, in _doFit
self._eval, self.xx, self.yy, p0=self.guess, sigma=self.sems)
File “C:\Program Files (x86)\PsychoPy2\lib\site-packages\scipy\optimize\minpack.py”, line 723, in curve_fit
raise ValueError(“sigma has incorrect shape.”)
ValueError: sigma has incorrect shape.

Any idea what’s going on?
Thanks for your help