Define program indicators without NA events

Dear DHIS2 community,

I am setting up an Event program (no tracked entities - DHIS2 version 2.24) and I just started to create program indicators.

For example, I have a question with two possible answers: Yes = 1, No = 0

I also have a certain amount of “Not Applicable” (N.A) answers in the total of submissions that I don’t want to take them into account in the calculation of the program indicator.

How can I do that?

Because when I create a program indicator such as :

Expression = Count of Event

Filter = [ID Data element] == 0 (as for the “No” answers)

It takes into account also the N.A and I don’t get the right amount.

With the “yes” (= 1) answers, I don’t have this problem.

Many thanks,