EDIT: Nvm i just missunderstood the sorting thing

This seems to have a Bug in the sorting.

"In the result, substrings will be in decreasing order of their length and when they have the same length sorted in ascending lexicographic order"

means that with these 2 sentences:

"looping is fun but dangerous"
"less dangerous than coding"

it should output "1:ooo/1:uuu/2:sss/=:nnn/1:ii/2:ee/2:dd/2:aa/=:gg" because the e comes before d and a in sentence 2
but the Test says it has to be "1:ooo/1:uuu/2:sss/=:nnn/1:ii/2:aa/2:dd/2:ee/=:gg" were a comes first then d then e

it follows no logical order

Your code not working is not a kata issue. An issue is a bug in the kata. It's hard to help since you give very few elements, you haven't even said which language you were using. Apparently, your code has a problem with some empty sequence. Please read the official documentation where you can find some helpful tips to debug your solution and maybe see how to post questions more efficiently: https://docs.codewars.com/training/troubleshooting/

C#
in my IDE it worked all fine...
when i click Test it says All Tests passed (There is only Test1 Basic Test)
when i click Attemp it says Test1 Basic Test failed and Test 2 passed (InvalidOperationException:Sequence contains no elements)

PLZ help me >.<