What OS are you using, win10 64bit?) Are you using the latest (installed) vapoursynth version? Typing python -V in powershell or cmd works?
I don't really see what I'm missing right now. I tested it on a another pc and everything is working fine. Maybe the debug build will provide more usefull information
https://www.dropbox.com/s/qy398voe4d...debug.zip?dl=1