Can't pass Calculate Client Security Hash

I complete the tasks and follow the PDD but I have some error at the end of excecution (exception).
I tried to upload on

but I don’t pass the exam. Someone can help me please?

Here there is my work:
https://www.mediafire.com/file/ycz6uda6czdwu9a/85d41d43abd3f69150876f4ca94414b51534578b.zip/file