I bought a Holga Pinhole Lens for Nikon DSLR. I attached it to my Nikon D7000 as described in the manual, set my camera to Manual, and the selection wheel to S (shutter preference). Camera is switched on, lenscaps have been removed. I should be able to set the shutter time with the wheel at the back of the camera, but I can´t. Also the shutter button doesn´t work. The Holga Pinhole Lens is supposed to work with the Nikon D7000, so apparently I´m doing something wrong. But what? Who can help? Thanks!