Some weeks ago I faced this problem, I had the task of SUM all element on a single sheet in a RPT file of reporting services.
After looking for the solution trying and failing, I found the way and here I give you the glue.
First, when we add TextBox Element on our group, it is created with a name which appear right down the property title in the property windows. This name is important for us to make all this possible.
Textbox selected inside the group:
Property Windows of the Textbox selected.
Feel free to change that name of the textbox, now we simply SUM the values in the sheet using the object: ReportItems as shown in below:
=Sum(ReportItems!Textbox1)
Now adding this to the element localized out of the group scope we will be able to sum all amount inside a group in the same sheet.
See you soon.
