Oh, you have a problem with the metal contacts. You can go online, excellence network or Jingdong Mall, photography / video, there are selling Alma contact guide agent, that is a special rub the camera contacts of the thing, buy it, take it to smear the metal contacts, the problem is solved, it will not not recognize the lens.
Don't ever take an eraser, ever!!!! Oh
It's also available on taobao