i'm having a problem by drawing a combined bar/line graphic with 2 dimensions and 2 measures. The second measure is drawn above the first dimension categories, instead of being drawn above the second dimension categories.
Unfortunately as far as I know this isn't possible; I've come across the same problem myself.
It's something that should be achievable as other packages (Tableau) do offer this ability and it shouldn't be too difficult. I'd recommend raising it as an Idea and linking back to this post.