1D4 Flash Control PC output problem

I tried to use 2nd Curtain for flashlight, and set in the manuel for 2nd curtain, however, I found that the PC wire connection output will only trigger at the 1st curtain, not at 2nd curtain. As in Studio, it is quite usual to use the PC connector to trigger flashes, do not know why it cannot provide the 2nd curtain flash syn. When using 580EXII at the hot shoe, there is no problem.

Is it possible that there is so setting inside I did not aware?