.bind tkinter python

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):
 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

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

You can also use the “preformatted text” tool in the editor ( </> ) to add backticks around text.

See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (’).