I created several hierarchy in the model. When I pulled the columns (not hierarchy) to the answer, some of them works fine with the Drill Down. Then I found that if the hierarchy has only 2 levels, the Drill Down just didnt work even I choose the "Drill" in Interaction tag. Anyone have the clue about this? thanks!!
2.) If you have this behaviour you either already have the atomic key column included in the analysis (and hence a drill becomes unnecessary - what would you want to drill TO when you're already at the lowest level?) or the setup of your logical dimensional hierarchies is invalid.