Your screen shot looks like a portal. Is it? Is it a portal to LineItems or some other table?
In what table is your calculation defined? Is it a calculation field or a number field with an auto-entered calculation?
You describe two fields:
RemainingCosu2=If(Invoice Line Items::Product Info1 = GetAsText ("N"); Sum(Cost Total) - Invoice Line Items::VendPaid_total;0) RemainingCosu1=If(Vendor Status="Partly Paid"; RemainingCosu2; 0)
Which column is RemainingCosu2 and which RemainingCosu1 in your screen shot?
In the first calculation, What you have posted does not look like the complete calculation. It looks like part of an If or Case function and if you tried to use exactly what you posted, you would get an immediate error message.
Also Sum (Cost Total) does not make sense. I suggest looking up the Sum function in FileMaker help. What you have written could be re-written as: Cost Total - Invoice Line Items::VendPaid_total
instead of Sum ( Cost Total ) - Invoice Line Items::VendPaid_total