Fixed ISI after correct response

I have been working with a serial reaction time task on superlab. In the task, 4 visual cues appear in random/sequential order. The subject is asked to press the correct button every time one cue - black square - appears on the screen. Time of response is recorded. The task has worked fine but now I want to delay the appearance of the next cue 400ms after the subject has pressed the correct response button. I cannot find this option in superlab although it seems obvious. Can anyone help?

Create an ISI event that lasts 400ms. Then, in the event editor for the black square, click the Feedback tab; when the response is correct, present the ISI event.

Thanks a lot