Beyond the commments about why the comparisons don't work as expected, I would like to point out that if you were to use if-elsif-else conditionals, you could dump the use of labels and last and make the code a bit shorter as well as more readable. You can check out perlsyn for more information on control structures in perl.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1