Sorting of numbers gives a random order in cross table

Question

I am having an issue with a cross table that I would like to sort. On the vertical axis I have some categories, and on the horizontal axis I have time. The table itself is filled with the value that is related to the previous two. I created a rank, which seems to be correct, but when I sort that rank, I seem to get a random order of numbers (example is the upper 10 for ascending order):

4971 - 420 - 4959 - 1 - 4969 - 4970 - 16 - 2 - 7 - 420

The value I ranked is somewhat odd:

=Last([X]) - Last(Previous([X]))

Where X is a measurement.

I already checked if I am using other sortings that I might have overlooked, but this is not the case. Also I am sure that this ranking is a number. I use merged items for the categories, and I used the combines object instead of one of the 'childs'.

Can someone tell me what I am overlooking?

I am on BO 2016, SP2.

Answer 1

The issue is solved by making a variable Delta which is =abs(Previous[X]-X). I also made a new variable that shows the current time, and I sort on Delta where the current time is equal to the time in the last column.