Hello guys. I need help. I have a Nikon D5300 and I am trying to use it with a macro extension tube. After i have put the tube, in the viewfinder I can see a proper exposure and I am also getting the macro effect but after I click the picture the screen only shows a black image. I think it has something to do with the aperture settings, and it seems the the lens is stuck at the highest aperture settings and hence very less light is able to pass through it. How do I prevent the lens from getting stuck at the highest F stop. I have also experimented with setting the lowest aperture before removing the lens from the camera but it doesn't help. Kindly advise.