[Tkinter] On Win 10, no graphical window when run code

[ma2020uk]

Hi
I am learning Python TKInter GUI.
I run following code on my Desktop running windows 10. The code runs but no root window appears.
If I run same code on my laptop, it works fine.
I use Sublime text. I also use Atom. Same problem with both.
I installed newer python-3.9.0-amd64 . Before I was using 3.8.2-amd64.
Problem still the same.
My computer has graphics card recently installed : ATI AMD Radeon HD 7000 series
Previously I was using motherboard graphics when I did not have this issue.
Could the card be causing problem ?
Help !

from tkinter import *

root = Tk()
myLabel = Label(root, text = ' Hello World !')
myLabel.pack()
root.mainloop()

Larz60+ write Nov-01-2020, 06:05 AM:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button.

I fixed for you this time. Please use bbcode tags on future posts. Thank you.