One of the newest feature of 11G is the possibility to expand/collapse hierarchy level (yep.. even in 2014 it seems to be a killer feature…heh!). The problem is you can’t display the hierarchy and the column used to build the hierarchy at the same time with a table. The hierarchy will be OK but the columns will display null value.
Suppose the Hierarchy Year -> Month -> Week -> Day
Add the hierarchy AND the columns used to build it like this:
As you can see, Month and Week are empty. This is caused by the Hierarchy.
et voilà !