"I think I understand your issue but without being able to see the code behind your Dataset and Also how you have laid out your data in your RDL this make s things difficult."
I see the confusion, the sample data is actually both the report layout and the dataset.
Widget factory 1- factory group header
Widget type 1 50
Widget type 2 75
Widget factory 1 total widgets 125- factory group footer
Widget factory 1 area 1000 sqm- factory group footer
Widget factory 2
Widget type 3 45
Widget type 4 55
Widget type 5 35
Widget factory 2 total widgets 135
Widget factory 2 area 5000 sqm
Total Widget factory area 6000 (17000)- total factory area showing both the desired figure and the figure I currently get (in brackets)
So, widget factory 1 produces 2 types of widget giving two rows (detail or sub group it doesn't really matter) for widget factory 1 so for factory 1 we multiply the factory area (1000sqm) by two to get 2000sqm.
Widget factory 2 produces three types of widget giving three rows so we multiply the factory area (5000sqm) by three to get 15000sqm. Then we add 15000 to 2000sqm to get a grand total of 17,000sqm for widget factory 2.
What is required is for me to know the total area of all my widget factories that are making my widgets. I have two factories (widget factory 1 and widget factory 2), one with an area of 1000sqm and one with an area of 5000sqm therefore the total I am after is 6000sqm so what I really need is to sum the factory area once for each occurrence of the factory group rather than once for each detail/sub group row, i.e. I need to sum my grouped data.
After some further hunting around I see that this has been asked before...
thanks for putting forward some ideas - I think I'll just put this to bed