this would be easier as an expression:
right click the intensity in the channel box and add this:
if(frame % 30 == 0)
{
pointLightShape1.intensity = rand(0,5);
}
What you are doing is using the modulus function (%) to check if the frame divides equally by thirty and then setting the intensity by expression.
Simple
Alan
Technical Director - Framestore
Currently working on: Your Highness
IMDB