Running total field ?

Hello Everyone,

How do I get Running total field? Below is my formula which is calculating testing_diff and I want to get SUM of that testing_diff variable.

HTML Code:

---

whileprintingrecords;
global numbervar testing_diff;
numbervar temp;
temp := cdbl({Online - Sale Bill_ttx.StockRegEntries-mrp} * {Online - Sale Bill_ttx.StockRegEntries-quantity}) - cdbl ({@prodAmount});
testing_diff := testing_diff + temp;
temp;

---

plz help me.... thanx in advance..... :rolleyes: