Help with using sub to update hash

["Mike Martin" <redtux1 googlemail com>]

I have the following code

#caller;

my %titles;
my %dvd_titles;
$dvd_act_btn->signal_connect('clicked'=>sub{$count++ &&
&dvd_setup($vbox2,$count,$sel_opts_vbox,\%titles,\%dvd_titles)});

#sub called

sub dvd_setup {
my ($vbox2,$count,$sel_opts_vbox,$titles,$dvd_titles)= _;
my $subname='dvd_setup';
#my %dvd_titles;
my %dvd_titles=%{$dvd_titles};
my %titles=%{$titles};
foreach my $keys (keys %dvd_titles){
print $keys,"=",$dvd_titles{$keys},"\n";
}
print scalar %dvd_titles;

foreach my $titles (sort keys %files){

if (${$files{$titles}}[0] eq $subname){
my $key=${$files{$titles}}[5]->get_active_text;
my $file=${$files{$titles}}[2];
unless (exists($dvd_titles{$key})){
$dvd_titles{$key}
};
push (@{$dvd_titles{$key}},${$files{$titles}}[2]);
}
}


foreach my $keys (keys %dvd_titles){
print $keys,"=",$dvd_titles{$keys},"\n";
}

}

However the hashes defined never get updated by the sub-routine "dvd_setup"

The hash is added to wuthin the sub (see later print lines), but
original hash is not getting updated.

Any help appreciated.