Почему срабатывает if?

Выводит "s is not in list"

from tkinter import *
from PIL import ImageTk, Image
from tkinter import messagebox
import pickle
win = Tk()
a = list

message_entry = Entry()
message_entry.pack()
s = message_entry.get()


with open ('massiv.txt', 'rb') as fp: 
    p = pickle.load(fp)
    print(p)


def xan():
    print("!")
    if s in p:
        o = message_entry.get()
        z = p.index(o)
        print(z)
        r = (p[z + 1])
        startedt_text.configure(text = r)
    else:
        print("else work")
        startedt_text.configure(text = "please repeat question")
        o = message_entry.get()

        startedt_text.configure(text =  "please write answer")
        b = message_entry.get()

        a.append(o)

        a.append(b)

        with open('massiv.txt', 'wb') as fp:
            pickle.dump(a, fp)


btn_reseach =Button(text="reseach answer", width=15, height=3,command = xan )
btn_reseach.pack()


startedt_text = Label(win, text="hello",font =("Arial Bold",50), bg = "gray", fg = "white")
startedt_text.pack()

win.configure(bg = "gray")
win.title("1")
win.geometry("900x600")
win.mainloop()