Hi, Have you tried the numeric equivalent of your times? I believe the if expression is interpreted as returning a number of seconds. The following table format line works for me:
#+TBLFM: $4=$3-$2;T::$5=if($4 > 0,29880,0);T::$6=$4-$5;T HTH, eric -- : Eric S Fraga (0xFFFCF67D), Emacs 24.3.1, Org release_8.2.5h-585-g5f0ca0
