Quiz answers sequence

I'm finishing my quiz with checkboxes but I've got one problem.
I've built a sequence (screeenshot with 2 possibilities but same result) to check the answers but sometimes it gives a wrong answer as correct.
The quiz has got 1297 questions, and I want for questions from 1 to 450 to put the correct answer in checkbox 3,
                                                                                    from 451 to 900 in checkbox 1,
                                                                              and from 900 to 1297 in checkbox 2.
I can't see the problem.

The structure for calling box 1  in the first example should have a parallel construction for the <1297 case ... that is you need to fence it off with   > 901   and  <1297  perhaps as you did for  451/900.

Try some blocks.

the second solution looks fine

in the first solution you better use <= 900 instead of >= 900

Thanks for the answers.
Despite Taifun was right (there was a mistake), I've tried all the possibilities but it keeps giving some wrong answers. I attach changes done.
Mistakes are usually in answers from 453 to 462 and from 876 to 986 (that is, close to when answers must change).
I've thought to change those answers in the text and put the correct answer in the new correct checkbox but when I test the app the old checkbox correct is marked as correct so the mistakes persist...
Is there any other way?

the second solution of your other screenshot was fine

if currentQuestion < 450 then box3

elseif currentQuestion < 900 then box1

else box 2

if you have problems, why don't you use "do it" to debug our blocks?

and remember: also check, if there are no warnings...