I am trying to get Access to calculate a remaining balance on a client based on information in multiple subforms, and keep getting a response of #Name. The formula I am trying to use is =([Site Info]![PO Value])+ Sum([Change Order]![Dollar Amount of Change])-sum([Invoice Info]![Value]). Any Ideas?

Try:

=(forms![yourmainform]![Site Info]![PO Value])+ Sum(forms![yourmainform]![Change Order]![Dollar Amount of Change])-sum(forms![yourmainform]![Invoice Info]![Value])

Thanks. After playing around with this for another 3 hours this morning, I got it by creating Subtotal fields on the subform, and copied the information to the main form to get this to work.