Incorrect percentages of grand total in waterfall

[Glen_]

Hi,

I'm getting incorrect standard margin percentages when trying to show the values in the waterfall as percent of grand total, I wondered if anyone could help?

I wonder if it's because our P&L lines are all stored in the same column in table "DATASHEETS" eg. I want our standard margin % but also within the data I have Gross sales, volume etc.  I can filter this out okay when showing absolute values, but it comes out incorrectly with percentage method

Here's a screenshot of how the data is stored if that helps:

Is there a DAX measure that can be written to solve and use instead?

Thanks for any support.