IIF Record =

I'm trying to update a query expression and not having much luck.

The origional expression pulled a value from a Form and then based on that
value summed the values from another table.

Month08: Sum(IIf(Forms![Summary Reports]![Report Month]=8,[Sep]+[Oct],0))

Now I want to point this expression to another table (not a form) in order
to retrieve the value. Basically I want it to read.

Month08: Sum(IIf([Export_Data].[Month] = 8,,[Sep]+[Oct],0))

Now the Export_Data table only has one record that I am manipulating via
VBA. Any help is greatly apprechiated.

Thanks!