my %counts={};

I think you need parentheses rather than curlies there. As it is, you are assigning a single hash reference to the hash, which it will then stringify and use as a key with no corresponding value. Also, if you use warnings;, I think you will get one complaining about odd number of elements in hash assignment, or words to that effect. Trying it I get this.

$ perl -MData::Dumper -Mstrict -wle '
> my %h = {};'
> print Data::Dumper->Dump( [ \ %h ], [ qw{ *h } ] );'
Reference found where even-sized list expected at -e line 2.
%h = (
       'HASH(0x817f880)' => undef
     );
$
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I hope this is useful.