AttributeError: 'NoneType' object has no attribute 'config'

Python TkInter
,
1 
     password = Label(frame1, text="Password", font=("helvetica", 15, "bold"), bg="white", fg="royalblue1").place(x=50, y=170)
    txt_password = Entry(frame1, font=("helvetica", 14,"italic"), bg="white",show='*').place(x=50,y=205, width=300)


    sifre=IntVar(value=0)
    def my_show():
        if(sifre.get()==1):
            txt_password.config(show='')

        else:
            txt_password.config(show='*')


    c1=tkinter.Checkbutton(frame1,text="Show Password",variable=sifre,onvalue=1,offvalue=0,command=my_show,bg="white")
    c1=tkinter.Checkbutton(c1.place(x=50,y=240))

BU ŞEKİLDE BİR KOD YAZDIM ŞİFRENİN GİZLENİP GÖRÜNÜR OLABİLMESİ İÇİN CHECK BUTTON OLUŞTURDUM FAKAT BU HATAYI ALIYORUM. ÇÖZÜMÜ NEDİR?

2

kodun düzeltilmiş hali:

password = Label(text="Password", font=("helvetica", 15, "bold"), bg="white", fg="royalblue1")
password.place(x=50, y=170)

txt_password = Entry(font=("helvetica", 14, "italic"), bg="white", show='*')
txt_password.place(x=50, y=205, width=300)

sifre = IntVar(value=0)

def my_show():
    if(sifre.get()==1):
        txt_password.configure(show="")
    else:
        txt_password.config(show='*')

c1 = Checkbutton(text="Show Password", variable=sifre, onvalue=1, offvalue=0, command=my_show, bg="white")
c1.place(x=50, y=240)

ve lütfen kodun tamamını paylaşın.