summary disable for specific fields

Hi Team,

We are currently using:-
BuildDate Wed Mar 05 15:52:00 IST 2014
Version 4.1p
SCVersionNumber v9.1p_2014-03-05


I have implemented grid summary function for my list grid by using
setShowGroupSummaryInHeader(true)

I have disabled right click 'group by' from few fields in my listgrid on some condition.
My requirement is that summary for these fields should not appear.

I am trying to use setSummaryFunction(SummaryFunctionType....);

Can you please suggest if that is the right way to do it?