tkinter button height and width

Question

I am trying to create a button and change the height and width using the code below but the actual button doesn't show physically. However if you hover over the area it is supposed to be and click it will open the new window. Any ideas?

import sys
from tkinter import *

#main menu
def mmWindow():
    mmWindow=Tk()
    mmWindow.geometry('600x600')


#first window   
mWindow= Tk()
mWindow.geometry('1920x1080+0+0')
mWindow.title('DMX512 Controller')

wtitle = Label (mWindow, text = "Pi DMX", fg = 'blue')
wtitle.place(x = 640, y = 100)

#main menu button
mmbutton = Button (mWindow, text = "Main Menu",command = mmWindow)
mmbutton.place( x=200, y = 200)
mmbutton.config(width=200, height=200)