Hi, I've recently bought a rubber collapsible hood for my Rollei 35 S. I bought it as a replacement to the one I had with the camera whose rubber was ripped. It's an original hood, exactly the same as the one I had on the camera. The only problem is that... I'm not able to mount it The hood is made by two parts: a threaded ring and the rubber collapsable part. without the rubber the ring can be easily screwed to the front lens. But when I put the metal ring inside the the rubber hood, where it is supposed to be, well... it's almost impossible to screw it on the lens, cause only a fraction of the threading emerge from the rubber... any suggestions?