How do I easily negate an expression in MS Report?

Question

I'm converting af Crystal report to a MS report. My expression in the Crystal report was like this:

=IIF(Fields!foo.Value Is Nothing and Fields!bar.Value Is Nothing,
0,
IIF(Fields!foo.Value Is Not Nothing and Fields!bar.Value Is Nothing,
Fields!foo.Value,
IIF(Fields!foo.Value Is Nothing and Fields!bar.Value Is Not Nothing,
Fields!bar.Value * -1,
IIF(Fields!foo.Value Is Not Nothing and Fields!bar.Value Is Not Nothing,
Fields!foo.Value,
0
))))

The Not does not work here, even thought the text is blue.

Can I use Not or something like !or do I have to go crazy with IsNothing()

Answer 1

You should be able to simplify your expression to:

IIF(Not Fields!foo.Value Is Nothing, 
    Fields!foo.Value,
    IIF(Not Fields!bar.Value Is Nothing,
        Fields!bar.Value * -1,
        0))

EDIT: To return foo.Value - bar.Value when neither is null, try:

= IIF(Not Fields!foo.Value Is Nothing, Fields!foo.Value, 0) -
  IIF(Not Fields!bar.Value Is Nothing, Fields!bar.Value, 0)