In &create() you get the address of the value in $hash{1}, which is only available within that scope. So when you try and dereference it in &extract() perl breaks because you're trying to dereference a non-existant value.
However if you directly pass address_of() $hash{1}, you'll get the expected reference. So this code will work

use strict;
use Devel::Pointer;

my %hash;
$hash{foo} = "bar";

my $ref = address_of($hash{foo});
print "reference : ".$ref."\n";

my $val = deref($ref);
print "value : ".$val."\n";

__output___

reference : 9900396
value : bar
[download]

The reason why you get a different reference value from address_of() each time is because you're creating a new scope, and a new value, so the reference will always be different.
I really wouldn't recommend using Devel::Pointer for day-to-day reference munging (hence the Devel), you ain't using C no more kid ;-) For some authoritative information on references in perl check out perlref.
HTH

broquaint