Not sure that's the right one. I've just got mine out of the box to have a look (before it gets shipped off to Poland). Have you put your thumb on the little lever plate thing below the lens (at about 5 o'clock)? Then it's just a question of pulling it forward, making sure that the lens doesn't lean forward on the hinge at the bottom otherwise it won't align with the tracks (which come out a little on mine).