弹出窗口中的Entry.get（）PYTHON不工作

Question

我做了一个弹出窗口，在一个函数中，我需要调用这些输入，但将它们打印为空白，有人知道这个问题，非常感谢

突然出现

 def popup_bonus(self):
    win = tk.Toplevel()
    win.wm_title("Window")


    #First Name
    win.labelFname = ttk.Label(win, text="First Name:")
    win.labelFname.grid(row=2, column=0)

    win.addFname = Entry(win)
    win.addFname.grid(row=2, column = 1)

    #Last Name
    labelLname = ttk.Label(win, text="Last Name:")
    labelLname.grid(row=3, column=0)

    win.addLname = Entry(win)
    win.addLname.grid(row=3, column = 1)

    #Course
    labelCourse = ttk.Label(win, text="Course:")
    labelCourse.grid(row=4, column=0)

    win.addCourse = Entry(win)
    win.addCourse.grid(row=4, column = 1)

    #Button
    cancelAdd = ttk.Button(win, text="Cancel", command=win.destroy)
    cancelAdd.grid(row=5, column=0)

    addTeacher = ttk.Button(win, text="Add", command=self.add_Teacher)
    addTeacher.grid(row=5, column=1)

在winodws中

def添加_教师（win）：

          print(win.addFname.get())
         #here always print in blank, obiously aferte write something