Well, the error you see is because you're returning a single number instead of 4 when there is a possible solution.

this one can return 53 - (28 + (21 / 21)), your answer is: 24

You should return '53 - (28 + (21 / 21))', not '24'

Print the input so we can check if it is a kata problem, and please, don't open multiple post about the same. Read this too.

Actually I just re-checked the wiki, it seems that the katas do give you a set amount of score (which you can see at the bottom of the page I linked above) based on the kata difficulty "as well as an internal score that counts toward your next rank" (this part I don't really get), my bad/

https://github.com/Codewars/codewars.com/wiki/Honor-&-Ranks#leveling-your-rank :)
No, problems don't show how many points they get you on completion. You get more "score" (which is different from Honor) the more difficult the kata is, but it also depends on your kyu. F.e. you, as a rank 8kyu, would get a lot more score from completing a 6kyu kata than I, as a rank 4kyu, would.