Hi - I give this exact example in my new book. I'm going to give you the overview here and you might be able to get it working. But to be honest, it's pretty complicated and there are a few pages of descriptions and explanations in the book. Also, I''m on vacation right now and didn't bring the book with me. So I'm going from memor yhere. If you can't get it working, then you should pick up a copy of the book.
Here's how it works: You have to have a formula that creates a global array for each column. Modify the cell in the cross-tab so that you attach a formula to one of the properties and that formula populates the array with the CurrentValue() function. Use the row/column value to determine which element in the array to populate.
Once you get to the last row, the first two columns in the array will be populated and then you can do the % calculation. Create a new formula doing the % calculation and attach it to the ToText property of the cell in the last column.
Again, this is a bit vague b/c I don't have my book with me to reference, but even if I did, it's too complicated to explain perfectly in a forum post. So hopefully, this will get you going in the right direction. If not, the book is a little more than $30 on Amazon and it will be the best $30 you spent.

You can find out more about my books at
Amazon.com
or reading the
Crystal
Reports eBooks online.
Edited by BrianBischof - 28 Mar 2008 at 9:45am