[Tutor] A simple problem with Tkinter

[Mark Kels]

hello,

I wrote this basic Tkinter code:

from Tkinter import *
root=Tk()
w=Label(root,text="Hello!!")
b=Button(root,text="Bye",command='exit')
root.mainloop()

But the output is an empty TK window (without the text and the button)...
What is the problem ?