Stackbar & Waterfall chart

[#1]

Hi All,

I have a Waterfall chart correctly displaying.   Using the Offset function to postion the components.

E.g. 

List-Rev    Rebates  Fees   Net-Revenue   COGS  Net-Margin.

I would like to make it stack bar by Product.    So  

List-Rev would be a stackbar for prod1..prodN

Same with Rebates.

However, I cannot seem to figure out what function to use for the offset.

For Rebates offset i tried sum(List-Rev)  anda sum(Total List-Rev).  with no luck.

Ideas.

Bernard