Check50 gives a green flag to a "Wrong" function

[4r13s2k]

In Tideman I came across a situation where Locked pairs function was not working properly. But later after testing manually I figured out that sort pairs didn't sort pairs at all. But check50 said it did. I've attached the code below.
(NOTE:- The code is in its unfinished condition. Currently I've found a way around it but the problem remains.)
chk50 bug.txt