How to Count a field with a certain expression applied

[#1]

Hey All,
I created an expression:

if((Count ( {< Dateentered = {'06/2009'}>} Service) - Count ( {< Dateentered = {'05/2009'} >} Service)) < 0 ) , 'Green', 'red')

What the expression does is it subtracts the count of services this month and the prior month and if it is less then 0 then green else it is red. What I would like to do is count how many of the services are green, but I am unsure how to even begin. I tried just counting the expression but I get a -. Any thoughts?

[#2]

Hi,

just an idea.

See the attached application.

Rainer