Captivate 6 advanced actions - a counter to know how many variables are not empty

I want to know how I can use an Advanced action to build a sort of "counter".

I have 10 "text entry boxes" allowing me to enter up to 10 participants names and I want Captivate to count, after having entered several names, the number of participants.

So, I already have 10 variables for the potential 10 participants + another variable called NumberPart (that should display the number of participants, after it has been use in the advanced action.

The 10 "participants" variables are empty when the project is launched.

The variable NumbPart value is initialize with 0 (zero) when we start.

I tried a conditional advanced action going like this :

Block Decision 1

If Part1 is not equal to 0  (I also tried: "" ; " "; TRUE ; FALSE)

     then

Assign NumbPart with 1

Block Decision 2

If Part2 is not equal to 0

     then

Assign NumbPart with 2

and so on...

This advanced action doesn't seem to work, mt NumbPart variable is always empty...

Any idea?

Thanks to everyone who can help me!

Jean Laurier