As per title recently took the hardtop off( about a month ago really) that when "plugged in" the rear demister worked fine so clear screen

. only recently I've been using the 986 for regular work travel. This means early starts and last week the rear glas was misted up. I pressed the dash switch to on it lit up but nothing happened.
My question is why should this happen? It may sound daft but do I have to plug in a harness from the soft top in to the pin socket the hardtop was connected to? If so where is it or should the window demist automatically once the hardtop is disconnected?
Only bought the car last November so not used the roof down to many times as the hardtop was fitted and working.
Any help as I would like to know were it is and if it works if not it needs addressing perhaps with a replacement? Cheers all.