Не могу вписать код регистрации, в дочернем окне, в чём причина?

Question

[Valeiy]

Сама программа

from tkinter import *
from child_window import ChildWindow
from tkinter import messagebox
from PIL import Image as pilImage
from PIL import ImageTk
import os

class Window:
    def __init__(self, width, height, title="MyWindow", resizable=(False, False), icon=r"icon/gerb.ico"):
        self.root = Tk()
        self.root.title(title)
        self.root.geometry("540x125+200+200")
        self.root.resizable(resizable[0], resizable[1])
        if icon:
            self.root.iconbitmap(icon)

        img = pilImage.open(r"icon/personal.png")
        img = img.resize((100, 100), pilImage.ANTIALIAS)
        self.photo_image = ImageTk.PhotoImage(img)

        img1 = pilImage.open(r"icon/podriydchik.png")
        img = img1.resize((100, 100), pilImage.ANTIALIAS)
        self.photo_image1 = ImageTk.PhotoImage(img)

        img2 = pilImage.open(r"icon/spravochnik.png")
        img = img2.resize((100, 100), pilImage.ANTIALIAS)
        self.photo_image2 = ImageTk.PhotoImage(img)

        img3 = pilImage.open(r"icon/info.png")
        img = img3.resize((100, 100), pilImage.ANTIALIAS)
        self.photo_image3 = ImageTk.PhotoImage(img)

        img4 = pilImage.open(r"icon/exit.png")
        img = img4.resize((100, 100), pilImage.ANTIALIAS)
        self.photo_image4 = ImageTk.PhotoImage(img)

    def run(self):
        self.draw_widgets()
        self.root.mainloop()

    def draw_widgets(self):
        Button(self.root, text="Персонал", image=self.photo_image, compound=TOP, command=self.button_action).grid(row=0, column=0)
        Button(self.root, text="Подрядчики", image=self.photo_image1, compound=TOP, command=self.button_action1).grid(row=0, column=1)
        Button(self.root, text="Справочник", image=self.photo_image2, compound=TOP, command=self.button_action2).grid(row=0, column=2)
        Button(self.root, text="Инфо", image=self.photo_image3, compound=TOP, command=self.finding).grid(row=0, column=3)
        Button(self.root, text="Выход", image=self.photo_image4, compound=TOP, command=self.exit).grid(row=0, column=4)

    def button_action(self):
        os.startfile("C:/Users/Валерий/Desktop/Doc/Список ФИО.docx")

    def button_action1(self):
        os.startfile("C:/Users/Валерий/Desktop/Doc/Подрядчики.docx")

    def button_action2(self):
        os.startfile("C:/Users/Валерий/Desktop/Doc/Телефонный Справочник.doc")

    def finding(self):
        messagebox.showinfo("info", "")

    def exit(self):
        choice = messagebox.askyesno("Выход", "Вы действительно хотите выйте?")
        if choice:
            self.root.destroy()

    def create_child(self, width, height, title="Child", resizable=(False, False), icon=None):
        ChildWindow(self.root, width, height, title, resizable, icon)


if __name__ == "__main__":
    window = Window(540, 125, "")
    window.create_child(550, 230, "Войдите в систему.")
    window.run()

Дочернее окно

from tkinter import *

class ChildWindow:
    def __init__(self, parent, width, height, title="MyWindow", resizable=(False, False), icon=None):
        self.root = Toplevel(parent)
        self.root.title(title)
        self.root.geometry(f"{width}x{height}+200+200")
        self.root.resizable(resizable[0], resizable[1])
        if icon:
            self.root.iconbitmap(icon)

        self.grad_focus()

    def grad_focus(self):
        self.root.grab_set()
        self.root.focus_set()
        self.root.wait_window()

Вот код который не могу вписать в дочернее окно

from tkinter import *
from tkinter import messagebox as ms
import sqlite3

with sqlite3.connect('quit.db') as db:
    cursor = db.cursor()

cursor.execute('CREATE TABLE IF NOT EXISTS user (username TEXT NOT NULL PRIMARY KEY,password TEX NOT NULL);')
db.commit()
db.close()


class main:
    def __init__(self, master):
        self.master = master
        self.username = StringVar()
        self.password = StringVar()
        self.n_username = StringVar()
        self.n_password = StringVar()
        self.widgets()

    def login(self):
        with sqlite3.connect('quit.db') as db:
            cursor = db.cursor()

        find_user = ('SELECT * FROM user WHERE username = ? and password = ?')
        cursor.execute(find_user, [(self.username.get()), (self.password.get())])
        result = cursor.fetchall()
        if result:
            self.logf.pack_forget()
            self.head['text'] = self.username.get() + '\n Добро пожаловать!'
            self.head['pady'] = 150
        else:
            ms.showerror('Авторизация!', 'В базу данных такой аккаунт не записан!.')

    def new_user(self):
        with sqlite3.connect('quit.db') as db:
            cursor = db.cursor()

        find_user = ('SELECT username FROM user WHERE username = ?')
        cursor.execute(find_user, [(self.n_username.get())])
        if cursor.fetchall():
            ms.showerror('Предупреждение!', 'Введите имя и пароль!')
        else:
            ms.showinfo('Регистрация!', 'Вы зарегистрировались!')
            self.log()
        insert = 'INSERT INTO user(username,password) VALUES(?,?)'
        cursor.execute(insert, [(self.n_username.get()), (self.n_password.get())])
        db.commit()

    def log(self):
        self.username.set('')
        self.password.set('')
        self.crf.pack_forget()
        self.head['text'] = 'LOGIN'
        self.logf.pack()

    def cr(self):
        self.n_username.set('')
        self.n_password.set('')
        self.logf.pack_forget()
        self.head['text'] = 'Реристрация'
        self.crf.pack()

    def widgets(self):
        self.head = Label(self.master, text='Автризация', font=('', 35), pady=10)
        self.head.pack()
        self.logf = Frame(self.master, padx=10, pady=10)
        Label(self.logf, text='Username: ', font=('', 20), pady=5, padx=5).grid(sticky=W)
        Entry(self.logf, textvariable=self.username, bd=5, font=('', 15)).grid(row=0, column=1)
        Label(self.logf, text='Password: ', font=('', 20), pady=5, padx=5).grid(sticky=W)
        Entry(self.logf, textvariable=self.password, bd=5, font=('', 15), show='*').grid(row=1, column=1)
        Button(self.logf, text=' Войти ', bd=3, font=('', 15), padx=5, pady=5, command=self.login).grid()
        Button(self.logf, text=' Регистрация ', bd=3, font=('', 15), padx=5, pady=5, command=self.cr).grid(row=2,
                                                                                                           column=1)
        self.logf.pack()

        self.crf = Frame(self.master, padx=10, pady=10)
        Label(self.crf, text='Username: ', font=('', 20), pady=5, padx=5).grid(sticky=W)
        Entry(self.crf, textvariable=self.n_username, bd=5, font=('', 15)).grid(row=0, column=1)
        Label(self.crf, text='Password: ', font=('', 20), pady=5, padx=5).grid(sticky=W)
        Entry(self.crf, textvariable=self.n_password, bd=5, font=('', 15), show='*').grid(row=1, column=1)
        Button(self.crf, text='Зарегистрироваться', bd=3, font=('', 15), padx=5, pady=5, command=self.new_user).grid()
        Button(self.crf, text='Назад', bd=3, font=('', 15), padx=5, pady=5, command=self.log).grid(row=2,
                                                                                                   column=1)

if __name__ == '__main__':
    root = Tk()
    root.title('Войдите в систему')
    main(root)
    root.mainloop()