PIN面板显示“PIN错误”信息,无论PIN是否正确

我有一个任务是在GUI中制作PIN面板,该面板应该检查PIN是否正确,并给出“正确PIN”或“错误PIN”的消息。我设法编写了整个代码,但即使我写了正确的PIN,它也会返回“错误的PIN”消息。

我试图更改字符串和整数中的PIN类型,更改调用函数check_PIN()的位置,但我总是得到相同的(错误的)输入

代码:

from tkinter import *

root = Tk()
root.geometry ('800x300')
root.title('Check PIN')

number1_var = StringVar()

def button_add(number):
    number1 = entry_PIN.get()
    entry_PIN.delete (0, END)
    entry_PIN.insert (0, number1+str(number))

pin = '1234'

def check_PIN():
    number1=number1_var.get()
    if number1 == pin:
        label1 = Label (root, text='Correct PIN!')
        label1.grid(row=6, column=1)
    else:
        label2 = Label (root, text='Wrong PIN!')
        label2.grid(row=7, column=1) 

label_pin = Label (root, text='PIN:')
label_pin.grid(row=0, column=0, padx=10, pady=10, sticky='e')

entry_PIN = Entry(root)
entry_PIN.grid (row=0, column=1, padx=10, pady=10)

button1 = Button(root, text='1', width=7, command=lambda: button_add(1))
button2 = Button(root, text='2', width=7, command=lambda: button_add(2)) 
button3 = Button(root, text='3', width=7, command=lambda: button_add(3))
button4 = Button(root, text='4', width=7, command=lambda: button_add(4))
button5 = Button(root, text='5', width=7, command=lambda: button_add(5))
button6 = Button(root, text='6', width=7, command=lambda: button_add(6)) 
button7 = Button(root, text='7', width=7, command=lambda: button_add(7))
button8 = Button(root, text='8', width=7, command=lambda: button_add(8))
button9 = Button(root, text='9', width=7, command=lambda: button_add(9)) 

button1.grid(row=1, column=1, padx=10, pady=10)
button2.grid(row=1, column=2, padx=10, pady=10)
button3.grid(row=1, column=3, padx=10, pady=10)
button4.grid(row=2, column=1, padx=10, pady=10)
button5.grid(row=2, column=2, padx=10, pady=10)
button6.grid(row=2, column=3, padx=10, pady=10)
button7.grid(row=3, column=1, padx=10, pady=10)
button8.grid(row=3, column=2, padx=10, pady=10)
button9.grid(row=3, column=3, padx=10, pady=10)

button_check = Button(root, text='Check PIN!', command=lambda:check_PIN())
button_check.grid(row=5, column=1)

root.mainloop()

感谢您提前回复!