How can I set KbWait to wait 5 seconds for an input, and if none, move on in Psychtoolbox?

Hi,

I'm trying to use KbWait in an experiment. The subject must make a key press within 5 seconds, or the experiment will move on. I obviously tried KbWait(5), but that does not work. Should I create some sort of an if statement with the time?

Thanks!