Dax formule Total

Hi, 

I have created a matrix with various dax formulas (total, total -1 month, verschil), now I want to add a new formula to add positive amounts (POS) (based on difference) and negative amounts (NEG). Like the attached example. Only the DAX I created shows the yellow shaded amounts. The total is not properly included with POS and NEG, here it is looked at total.  I briefly recreated the matrix in excel to clarify my question.

Thanks!