Crosstab: Calculated Field varies per Cross Tab Column

[chaycka]

Hello all,

I had been battling this problem for 3 days now and I am hoping I can get some help here. I am new to Cognos so I my problem might be easy to fix or impossible to implement.

I have a cross tab, that list the following:

QT1 QT2 QT3 QT4 Half1 Half2 Sum
Revenue 10 5 6 7 15 13 28
Margin 3 2 1 3 5 4 9
GP 30% 40% 17% 43% XX% XX% 32%

Both QT and Half columns are created via Case statement as buckets to put my data in.
Margin is calculated as "Revenue - Cost"
GP is calculated as "total([Margin] for [QT]/total([Revenue] for [QT])"

The GP for QT column returns correct value, however the GP for Half column, obviously, returns incorrect value.

What can i do so that I can have GP Calculated DataItem return
"total([Margin] for [QT]/total([Revenue] for [QT])" for all QT columns
and
"total([Margin] for [Half]/total([Revenue] for [Half])" for all Half columns?

Or maybe there is another way to do this?

Thank you very much in advance for your help

Natalya