Python tkinter grid problem?

There seems to be some problem with the grid geometry manager, or maybe its just my syntax thats incorrect. Im using Python 2.3.4. My problem is that even when I use the sticky='news' option in any grid method, it just doesnt work period. For example, the following code gives be a window with a small button in the middle. The desired effect was a button whos size matched the size of the window.

# import resources
from Tkinter import *

# the root window
root=Tk()
root.geometry('200x100')
root.title('Grid Tester')
root.resizable(0, 0)
# the tester frame
tester=Button(root, text="Test")
tester.grid(row=0, column=0, sticky='nsew')

# the event loop
root.mainloop()

I have tried a few other things such as, sticky=NSEW, sticky=nsew, sticky="NSEW". I hope it doesnt matter what order you put them in.. Please let me know if this is a problem with my syntax, and correct me if so. Also, this is my first post on unix.com so... HELLO EVERY ONE!