Andre:

Yes, "Total Dollar Value" will always be positive. You need to look at the type of Document and reverse the sign if it is a Credit Note.

That is what Michael's formula does. If the Document is "C", then switch the sign. And this is exactly what you did with your "True Amount" calculated column.

I believe that you and Michael are in agreement, just expressing yourselves differently.

The only question is why you weren't able to use your "True Amount" column to calculate your commission amount. As David said earlier, that will work. For instance: {True Amount} * .10 will give you proper figures.

Of course, since you have a calculation that works, why change it?