I believe that you're running into operator precedence problems between the 'if' modifier and the => operator. Instead, try a grep in there as well:

my %hash2 = map { $_ => $hash1{$_} }
            grep { defined $hash1{$_} } @ary;
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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain