There is a space at the end of the string that your function is returning.

Hello.

First of all, it would be nice to know what programming language you are using. Second, it would be a lot more helpful if you descripted what your code was doing wrong, rather than just paste your code into the chat. If you don't have to mark your message as spoiler, more people will be able to see it and help you.

I assume that I know the answer your your issue though. It is a very common mistake that people do in this kata, not knowing the difference between sorting a list of numbers verse sorting a list of strings.
You can see an example used to explain it here.

The comment right underneath yours even asks the same question.