Just changed my cabin filter but was surprised to find the filter tray empty when I took it out. I've fitted the new one, having followed instructions on you tube, but have noticed that my filter tray is not the same as the one in the clip. The one on the you tube clip has an open bottom section so the entire filter takes air, but on mine my tray has a plastic base with a circular hole cut into it, so not all of the filter will have air coming through it. Very odd, I think. Can anyone shed any light?