erorr 1 jan 1970 in izap-user-points

in izap-user points i look error in save offers date 1 jan 1970 . I think erorr in file /izap-user-points/actions/admin/save_redeem_coupon.php in this fragment code str.34

$time = split("[\/-]",$posted_array['valid_till']);
$time_str = mktime(23,59,59,$time[0],$time[1],$time[2]);
IzapBase::updatePostedAttribute('valid_till', $time_str);

What think?