- $row->{invnumber}{link} = build_std_url("script=$ref->{module}.pl", 'action=edit', 'type=invoice', 'id=' . E($ref->{trans_id}), 'callback');
+ $row->{invnumber}{link} = build_std_url("script=$ref->{module}.pl", 'action=edit', 'type=invoice', 'id=' . E($ref->{trans_id}), 'callback') if ($ref->{invnumber});