This is really weird. I want to divide Amount by Units to get the average
amount per unit. So I used this:
=IIF(Fields!UnitsBilled.Value = 0, Nothing, Fields!AmountBilled.Value /
Fields!UnitsBilled.Value)

Pretty standard stuff. I have three other calculations on the same report
that do much the same on different fields and work perfectly. However, when
UnitsBilled = 0, I get #Error for the entry in the table rather than Nothing
and VS2003 reports a divide by zero error. Changing the Nothing part of the
clause to 0.0 or "Nothing" still has the same effect. It appears the false
part of the statement, the division calculation, is still being done even
when UnitsBilled = 0.

UnitsBilled and AmountBilled always have a value - there are no Nulls in my
data. Changing the test to Fields!UnitsBilled.Value = 0.0 has no effect.

So the test for UnitsBilled = 0 is failing, which means that UnitsBilled is
not zero, so the false part of the IIF statement, the division calculation,
is being done, resulting in a divide by zero error because UnitsBilled is
zero! Under what circumstances does zero not equal zero?

If I use the following calculation, it works fine (that is, when UnitsBilled
= 0 I get Nothing in the table's textbox):
=IIF(Fields!UnitsBilled.Value = 0, Nothing, Fields!UnitsBilled.Value)

If I change the calculation to this, I get NaN when UnitsBilled = 0:
=Fields!AmountBilled.Value / IIF(Fields!UnitsBilled.Value = 0, Nothing,
Fields!UnitsBilled.Value)

However, what is really weird is that when I use the following bizarre
calculation I get the desired result of Nothing in the table's textbox when
UnitsBilled = 0:
=IIF(Fields!UnitsBilled.Value = 0, Nothing, Fields!AmountBilled.Value /
IIF(Fields!UnitsBilled.Value = 0, Nothing, Fields!UnitsBilled.Value))

Environment is SQL Server 2000, RS2000 and VS2003.