You may want to try and add some debug stuff for instance

$unique_events_sth = $db->prepare( $UniqueDay ) or die "Unable to prep
+are query : $DBI::errstr";
$unique_events_sth->execute($Month, $Day) or die "Unable to execute qu
+ery : $DBI::errstr";
[download]

Then the script will die and print some any error message.