Use of uninitialized value in concatenation (.) or string at parse_voter_list.pl line 251

##</code><code>##

if(!defined($mlg_addr_id) && length($fields[20]) == 2){
    $sth_insert_mlg_addr->execute(@fields[17..23])
        or warn "While inserting new mailing address |$fields[17]|; |$fields[19]| |$fields[20]|, with id |$mlg_addr_id|: " . $dbh->errstr;