Help with Morsematics (MorseV2)

I have trying to get this module to wrok way too many times, and it's always wrong, i don't know if im missing a step but it always ends up being wrong.
I first get my 3 displayed letters, then get my character pair. I slowly modify the character pair following the rules, and when inputing the letter, it gives me an error. It's just never right.