especially Data::Dumper should help you greatly in finding the problem

In my opinion, Data::Dumper is the end-all-be-all solution to the 'my-data-isn't-what-I-expected' problem. It can help you to solve all sorts of riddles, from a malformed hash, to using a variable out of scope and not being able to figure out why it's always null.

As mentioned above, definitely use strict and warnings. The perl interpreter is usually very good at detecting when you've done something that you didn't want to, at least when it comes to misusing assignments, scope violations, etc., but you'll never see those messages without those directives.