Cube View Row Math?

Hello all,

I've written a Member Filter Builder on A#IncomeStatement.Base.Where(AccountType Contains Revenue).  A second one for Expense too. I am now trying to sum those rows and cannot seem to get the math logic to render. Any advise out there - what am I missing or not considering? Columns are Entities, not row/column sharing, and the number of rows are extensive.

I've tried the following and cannot seem to get it right:

GetDataCell(CVR([TB_Rev])):Name(Total Revenue)

GetDataCell(A#IncomeStatement.Base.Where(AccountType Contains Rev):Name

Thanks in advance for your help,