Add addional data on top of bar chart data

[rosie]

How do I add a dotted/shaded stack on top of an existing one.
Ex:

I have 2 stacks that represent revenue shipped in each of 4 Quarters .
Then in the next quarter I have revenue shipped to date.
Now I need to add projected revenue to ship on top of the shipped data in
this 1 Quarter only. The bottom data ( shipped to date ) is a solid color,
and I need to be able to show the projected data on top either shaded or in
some other method so you can see the shipped to date with the projected in
top clearly.