My pie chart displays data from a dataset properly right now. What it displays is a sum of materials for a day, grouped by material name.

For example:

LTV - 5000 pounds - 1/1/2010
LTV - 4000 pounds - 1/1/2010
HAT - 2000 pounds - 1/1/2010
HAT - 2200 pounds - 1/1/2010

It sums by material. So in essence I have 9000 LTV and 4200 HAT. The piece that I am missing that I need to add is the "empty space" available. The empty space is simply the Capacity minus the totals above. So if the total capacity is 15,000, I need to take 15,000-13,200(totals of LTV and HAT above) and add 1800 "empty space" to the pie chart.

As I said before, the pie chart works fine displaying the sum of the materials. I have added a parameter to the report with static capacity numbers. How would I subtract the totals of LTV and HAT from the Parameter and display that number on the pie chart? This was all done with the designer as well so far.

Thanks!