Tkinter exception if entries are not filled up

[Reldaing]

Hi, he're my request: I want that if all the entries are not filled , the button stays disabled and if not, the button enables. I tried to but I didn't manage it. Could you tell me what's going wrong and how to solve it ? Thanks:

    label1 = Label(Appli,text="Entrez votre nom: ",font=("arial",12,"bold"),bg="#2340B6", fg="white")
    label1.place(x=20, y=100)
    i= StringVar()
    entry_box1= Entry(Appli, textvariable=i, bg="white", width="15")
    entry_box1.place(x=190,y=105)


    label2= Label(Appli,text="Quelle est votre année de naissance? : ",font=("arial",12,"bold"),bg="#2340B6", fg="white")
    label2.place(x=20, y=175)
    k= IntVar()
    entry_box2= Entry(Appli, textvariable=k, bg="white", width="15")
    entry_box2.place(x=340,y=180)


    label3= Label(Appli,text="Quel est votre revenu mensuel sur vos six derniers mois? : ",font=("arial",12,"bold"),bg="#2340B6", fg="white")
    label3.place(x=20, y=255)
    revenu_moyen= IntVar()
    entry_box3= Entry(Appli, textvariable=revenu_moyen, bg="white", width="15")
    entry_box3.place(x=500,y=260)


    label4= Label(Appli,text="Combien de trimestres avez vous cotisé? : ",font=("arial",12,"bold"),bg="#2340B6", fg="white")
    label4.place(x=20, y=335)
    trimestre_cotisés= IntVar()
    entry_box4= Entry(Appli, textvariable=trimestre_cotisés, bg="white", width="15")
    entry_box4.place(x=380,y=340)


    label5= Label(Appli,text="Combien avez vous d'enfants? : ",font=("arial",12,"bold"),bg="#2340B6", fg="white")
    label5.place(x=20, y=410)
    enfants=IntVar()
    entry_box5 = Entry(Appli, textvariable=enfants, bg="white", width="10")
    entry_box5.place(x=300,y=415)







 
    def do_it():
        if i.get() and k.get() and revenu_moyen.get() and trimestre_cotisés.get() and enfants.get()  :
            button["state"]= "normal"
            F= calcul_fonctionnaire(i.get(), k.get(), revenu_moyen.get(), trimestre_cotisés.get(), enfants.get())
            S=int(F)
            G=F*12
            RA=int(G)
    
    
            A= str(i.get())+", ta pension de retraite sera de "+str(S)+"€ par mois, soit de "+str(RA)+"€ par an"
    
            button.destroy()
            label6= Label(Appli,text=A,font=("arial",15,"bold"), fg="white", bg="#2340B6", bd=2, relief=SUNKEN)
            label6.place(x=40, y=500)
        else:
            button["state"]= "disabled"
    




    button= Button(Appli, text="Calculer", width="20", height="3",command=do_it,font=("arial",12,"bold"),bg="white",fg="#2340B6", state="disabled")
    button.place(x=20, y=500)