Group2 value to Group 1

Printed From: Crystal Reports Book — Forum Name: Technical Questions

Hello,
I have two groups define (Group1 and Group2)
Now i use suppress formula in group 1 and group2 as I do not want to display those department names on my report.
So currently my report looks as follow

Dept      Total        Diff
AA          20           40
BB          50           20
CC          20           10
AA11        60
BB11        70
CC11        30   

Dept (AA,BB,CC) are in Group 1
Dept (AA11,BB11,CC11) are in Group 2
Now Diff is a calculated column which is (AA11 total -AA total)
When I write a formula

@Diff
{@TotGp2} - {@TotGp1)    //Place it in group 1

Syntax wise it is correct but when its execute {@TotGp2} give me 0 (Zero)

Can some body please guide me as how do I store group 2 total for each department, so I can use it in group1 to find out Diff?

Thank you