Netgen GUI doesnot work

I have installed the newest version of Ngsolve on Windows: NGSolve-6.2.2004-win64.msi. . When I run my .py file to draw a mesh in Command Prompt, the Ngsolve GUI appears a few seconds, the it stops running automatically. No error notifications shows. Could you please tell me how to fix that issue? Thank you.

The reason that I had the error was I used the wrong command.
When I used python poisson.py, the GUI was unstable.
When I used netgen poisson.py, it worked perfectly.