Bar chart problem

I've got some data that I want to display as a bar chart.

I'm using the 'Stacked column' option to show how much budget has been allocated to something and how much of that has been spent.

What I can't seem to do is to add additional columns for different budget areas on the same chart. When I select the data it just lumps it all into one stacked column.

How can I specify that I want *these* two bits of data in the first column and then *those* two bits of data in the second column?

Many thanks,
Dave.