I think you are referring to the rubber gasket right? If so, I have to agree with Danny. You may want to put the rubber gasket on the outside as well. The pin space that goes on the outside has the little groove so that the rubber gasket is kinda flushed in place once you put it on to keep it from sliding off the glass. I won't say it doesn't work without it but I would be hesitant to not put the rubber gasket outside.