我用python制作时钟时出错了

from tkinter import *
from tkinter.ttk import *

from time import strftime

root = Tk()
root.title('Clock')

def time():
    string = strftime('%H:%M:%S %P')
    label.config(text=string)
    label.after(1000, time)

label = Label(root, font=("ds-digital", 80), background="black", foreground="cyan")
label.pack(anchor='center')
time()

mainloop()

我犯了这个错误

File "c:\Users\david\OneDrive\Desktop\practice projects\clock.py", line 16, in <module>
    time()
  File "c:\Users\david\OneDrive\Desktop\practice projects\clock.py", line 10, in time
    string = strftime('%H:%M:%S %P')
ValueError: Invalid format string