Hi
I got around this by taking a different approach. What you can do is use an expression to hide the row. What I had was rows in the dtail section of my report that were coming from both level 3 and level 4 of a hierarchary. I only wanted to display the rows from level 4, so I also went on the search to set the hight of all of those detail lines from level 3 to 0. But as you all has said that is not possible, but the other way is possible. I set the default row hight to 0.01 and set the option to allow the heigh to expand. Doing this the rows that are hidded stay hidden as they have no inherent hight, but the rows with values expand to be displayed.
Strange I know, but there you go. Hope that helps
Paul