I am quite sure you haven't written use strict in your script. Furthermore you are not viewing warnings if use warnings is on

How can you get any value in "brokers" when you have declared "broker" in the start of the loop!!!

Even if it would have been "broker" it would give compile time error under use strict

When you write %$broker{'engineWeight'} it will try to find the value of $broker{'engineWeight'} and will append to '%'. Since there is no hash like %broker (mind it - it is hash reference $broker) it will throw a compile time error.