How do I refer to instanced objects properties

I am generating 2 particles (objects) in a for loop. What I get are two instances named by actionscript (instance2 and instance4). Pictures of my code are below (2 files: main.as and particle.as).

 After compiling above code I am getting an error like on the picture below (I am assuming it can't recognize object name).

 If I move trace(circle[1]); from a loop back to particle(inc) function I am able to refer to object partialy like on the pictures below, but trace is not only checking circle[1] but also circle[0] for some reason.

 If I use trace(instance2 or instance4); then it is totaly not recognizing objects, look below