Object referee not set to an instance of object


I have the next problem, when I change my data with my form. I always get the error message: “Object reference not set to an instance of an object”

Can you help me?
I thinks I did not make the correct key. But the value is in the same column… so I don’t understand.

→ Error message

When I change the value of this column →

And the technicals of that column are one for update and change →

Can you guys please help me!

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