Again problem with data values

I observed that, analysing cortical results with pQCT pluging we obtain SSI (mean I suppose) that is the sum of SSIMax + SSIMin
For soft tissue, we can obtain a FatD of 0.18 with Fat area = 20.56 cm² and SubCutFatD = - 0.97 SubCutFatA = 18.07 cm²
Is there any bug in the calculation ?

Thanks for giving your thoughts