Error 11 at nikon camera

First, if you can try the lens on another camera body, please do. See if the same thing happens on a different camera body. If it does, it's a problem with the lens. If not, you need to look at the camera. You can verify it's the camera by placing a different lens onto the body and see if you're experiencing the same problem. If it is indeed the body, I would suggest you take a pencil eraser and gently but firmly clean the contacts located on the lens mount. It's my experience (I also shoot with a D200) that often times when a lens isn't autofocusing, it's due to direty contacts either on the lens itself or the camera body. Cleaning them is a good start though and will narrow your issues down to the lens or the camera body. After cleaning, try the lens again to see if it's working correctly. If not, send it to Nikon in New York for repairs.