Are you checking for errors? The best way to do this is to set RaiseError to 1:

# do a $dbh = DBI->connect(...)
$dbh->{'RaiseError'} = 1;
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Then you'll see any errors that your database engine is giving you.

Also, try dumping out the hashref that you're getting back:

use Data::Dumper;
while ($pointer = $sth->fetchrow_hashref) {
    print Dumper $pointer;
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That'll show you what fields you're getting in the hash ref that you get back. You might also think about using bind_columns, since it's faster. More details in Tricks with DBI.