10 Jul 2012 by Sandeep Mewara
Expression should be ok. I guess, there might be an error for the first row evaluation(as Previous for it will give Nothing).Try:=IIF(RowNumber("GroupbyCategory") Mod 2, Nothing, IIF(Fields!EventID.Value = 0, DateDiff("h",Fields!EventDateTime.Value, Previous(Fields!EventDateTime.Value)),...