Report Builder 2.0 Sort by Value Column

I have a drill down table and I can sort by the Group columns, but sort by the Value column (Quantity) doesn't work.

I'm right-clicking the header, selecting textbox properties, selecting interactive sorting, selecting Detail Rows, Selecting Sort By Quantity. I've also tried every permutation on the available options. Is there a trick to getting this to work?

Edit: I found this nice chart saying what to do in different sorting scenarios: http开发者_开发技巧://msdn.microsoft.com/en-us/library/dd207011(v=sql.100).aspx If I'm the 3rd case (not sure) of the chart, then was is a "child group header row"?

I figured it out. Sorting Details is not as simple as sorting groups. It looks like the 4th scenario in the chart linked above. These are the steps:

1) Right click the column header, select textbox properties, select interactive sorting.

2) Select Group under Enable Interactive Sorting...

3) Select the parent group to sort (the detail column is not a group so it's no listed) 4) (the trick) Under Sort By, use an expression that is an aggregate of the dataset field to sort by, which in my case was: =Sum(Fields!Quantity.Value)

Sorting Details is not really point and click like sorting Groups. I've seen a few other unanswered posts with similar issues, so I hope this helps someone else.