another perl question

Hello,
I can't figure out from the books why this does not produce a hash element:

$addresses{$lineref->[0]} = ($#cmdNode >= 0 ? $#cmdNode : 0);

perl -e '$lineref->[0] = "00401000"; $addresses{"$lineref->[0]"} =
(defined @cmdNode ? $#cmdNode : 0); print $#{keys %addresses};'

Thanks for any help!
--rod