dateentry Tkcalendar change the month and year repeatedly?

I'm using DateEntry from tkcalendar. The problem is that I can only change the month and year the first time. When I try to change the year or month a second time, the calendar immediately disappears. How do I change the month and year when I change the date repeatedly?

from tkinter import Tk from tkcalendar import DateEntry root = Tk() cal = DateEntry(root) cal.pack(padx=10, pady=10) root.mainloop()