I believe that only certain models will recognize this. I'm not sure which. I remember reading something here about that. What type of switch are you using? I ... think that only the Innovelli switches support that. But I am not sure. Search it here. You should find a thread on it.
I am using the physical detection on a GE dimmer, it depends on the switch and driver though, the logs on my switch differentiated between digital and physical. I set up a rule so when the on is physically pressed it will come up to full brightness since my wife didn't notice it came on when she pressed it but only at 16% which is what the last (night) motion rule set it to.