.bind tkinter python

Hello,
i used tkinter and created a f1 window (window f1 is activated by a window button f). Inside, I entered a text box:

 def click1(event):
        print(ampiezza.get()+1)
 ampiezza=IntVar()  
 casella1=Entry(f1,textvariable=ampiezza).place(x=80,y=50)
 casella1.bind("<Return>", click1)  

but i have the following error:

Exception in Tkinter callback
Traceback (most recent call last):
File “C:\Users\mazza\Anaconda3\lib\tkinter_init_.py”, line 1705, in call
return self.func(*args)
File “”, line 57, in sinusoide
casella1.bind("", click1)
AttributeError: ‘NoneType’ object has no attribute ‘bind’

can someone help me? thank you

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