SSRS why?

I've got three different reports, housing the same kind of information. Same expressions. One is working properly and the other two aren't.

The following is the code that works( and by works, I mean that it isn't listing ALL items, it actually "sums"):

=Microsoft.VisualBasic.Strings.FormatNumber(Sum(Microsoft.VisualBasic.Interaction.iif(Fields!DocDetailedCategory.Value="OTHER SUPPLIES - SPRINTER",Fields!ActualSum.Value,0)),0)

Now, I have the same code snippet in two other reports...and it's listing "OTHER SUPPLIES" five bazillion times (a little overdoing it, but still).

I've noticed that in the Tablix, one has a "(" and the other has the three horizontal lines next to the row. Would this be causing it not to work?

I amfar from the world's greatest coder, but I definitely need help, and well, I usually get great help here.

Please,...