I recently ordered a Nikkor 50mm f/1.8D lens for my N75. However, it does not seem to want to screw on to my camera body. My cheaper "G" lens goes on fine, but I cannot seem to get the 1.8 on. I am aligning the mounting dot on the lens with the one on the camera, but when I turn couter-clockwise, it seems to be stuck. It goes a few millimeters, then meets very stiff resistance. I do not want to force it, because I am afraid it might break. Any ideas on what I may be doing wrong?