Expressions: IIF and Replace Statments

HI,

Currenlty,I have an expression:

=Replace(Space(6) + Fields!ABC.Value," "," ")

Now, I need to replace the value that says "Hello" to "GoodBye".

If the spaces weren't needed, I know to write the expression as:

=IIF(Fields!ABC.Value = "Hello","Goodbye", Fields!ABC.Value)

but how do I make this change and still keep the spaces?

I have tried several ways and either I get #Error for all the values or I cannot preivew.

Please help!

Thanks!!