ROLLUP vs CUBE

Well, that's what happen when you don't carefully read the documentation. I have recently discovered the benefit of the WITH ROLLUP clause in SQLServer 2005, and I thought what it was doing was returning all possible combinations of grouping.
Wrong, that's the WITH CUBE.

Using the WITH ROLLUP I found out that the number of rows returned by my query was dependent on the order of the fields in the group by clause. Funny.

Well, to keep it short, I found this: http://msdn.microsoft.com/en-us/library/ms189305%28SQL.90%29.aspx
because "ROLLUP generates a result set that shows aggregates for a hierarchy of values in the selected columns" we get results depending on this hierarchy.

unlike it, what I needed was the WITH CUBE clause: CUBE generates a result set that shows aggregates for all combinations of values in the selected columns.