Well it turns out that i'm using System Compare Two Values. So it not picks as expected. In my example. I have:
System: abs(Object2.X - Object1.X) <= Value -> Object2.Var = Something
All Object2 instances get affected. Resuming what is happening is that my Object2 acts defined by an AI. But when an event triggers an action on one instance all other instances do the same action. Clearly a picking problem. I'll try to find a workaround.