This works OK for me:
=CountDistinct(IIf(Fields!column1.Value = "-", Nothing, Fields!column1.Value))
+ Sum(IIf(Fields!column1.Value = "-", 1, 0))
I'm using two aggregate IIf
expressions for the two cases.
The first is CountDistinct
against all the non -
rows, and the second is simply a count of all -
rows.
Seemed to work OK with all -
rows and with no -
rows.
Edit after comment
If you're using this expression outside of a tablix, you may need to specify the Scope of the aggregate:
=CountDistinct(IIf(Fields!column1.Value = "-", Nothing, Fields!column1.Value), "MyDataSet")
+ Sum(IIf(Fields!column1.Value = "-", 1, 0), "MyDataSet")