I try to set up a simple Target-Actual comparsion with MDX using the
following expression:

select
Crossjoin({[Szenario].[Actual], [Szenario].[Target]}, {[Measures].[Value],
[Measures].[Percentage]}) ON columns,
...

Now I want to add a column with the difference of the two measures
([Measures].[Difference]). I know how to calculate the difference but I do
not know how to write a MDX expression that adds a single column with the
difference to the right hand side of the table.

Does anyone have an idea?