Button don’t show

He, i am strugeling whit a problem ,
i wannel call the ok restrasion botten.
but it don't show on the screen. of form

i gows over this pies of code in the program.

    btn_ok_REG = Button(root_reg, height=1, width=7, text='Login')
    btn_ok_REG.pack()
    btn_ok_REG.place(x= 100 , y=50)


#!/urs/bin/evn python
from tkinter import *
root = Tk()
root.title("Main Form")
root.geometry("640x480")

def helloBack():
   msg = messagebox.showinfo( "Hello Python")

def registrastie():
    root_reg = Tk()
    root_reg.title("Registrasie")
    root_reg.geometry("400x400")

    btn_ok = Button (root_reg ,command=helloBack, height=1, width=7, text='Login')

    label_text_name = Label(root_reg, text="name : ")
    label_text_name.place(x= 101, y=50)
    label_text_userid = Label(root_reg, text="userid : ")
    label_text_userid.place(x=100, y=80)
    label_text_token = Label(root_reg, text="Paswoord : " )
    label_text_token.place(x=80, y=110)
    btn_ok_REG = Button(root_reg, height=1, width=7, text='Login')
    btn_ok_REG.pack()
    btn_ok_REG.place(x= 100 , y=50)

    lbn_name= Entry(root_reg, width=30 )
    lbn_name.place(x=150, y=50)

    lbn_userid= Entry(root_reg, width=30 )
    lbn_userid.place(x=150, y=80)
    lbn_token= Entry(root_reg, width=30 )
    lbn_token.place(x=150, y=110)

def login():
    root_login = Tk()
    root_login.title("Login")
    root_login.geometry("400x400")
    label_text_login = Label(root_login, text="User ID : ")
    label_text_login.place(x= 114, y=50)
    label_text_token = Label(root_login, text="Paswoord :")
    label_text_token.place(x= 100, y=80)
    lbn_name= Entry(root_login, width=30 )
    lbn_name.place(x=160, y=50)
    lbn_userid= Entry(root_login, width=30 )
    lbn_userid.place(x=160, y=80)
# login
btn_number_one = Button (root ,command=login, height=1, width=7, text='Login')
btn_number_one.pack()
btn_number_one.place(x= 100 , y=50)

# Registratie
btn_number_one = Button (root ,command=registrastie, height=1, width=7, text='Registratie')
btn_number_one.pack()
btn_number_one.place(x= 200 , y=50)

root.mainloop()
root_reg.mainloop()
root_login.mainloop()