Calculate difference between two dimensions Qlikview May 2021 SR1

[curiousfellow]

It seems my post disappeared (or I did not save it )

I have a pivot chart with columns contain a dimension and a (calculated) subdimension.

the subdimension values are not a part of the main dimension
Now I have to calculate the difference between dimension and dimension -1 . In my table I have a value "previous dimension"
I cannot find a way to make an expression that calculates the difference. 

[Chanty4u]

May be this 

Sum(Measure) - Above(Sum(Measure))