If the grey card, or in your case white paper, is filling up too much of the frame it could be causing this error. Back up and re-frame the shot allowing some blacks/whites to enter the frame, as well as the paper you're using to balance off of.I am using a white paper.
Jose
I don't see how it can hurt, although I'd be surprised if it solved the problem. Still, I don't really have any other suggestions for you. Good luck!Thank you very much for your answer.
I have done the way you say, I have also changed the lenses, but it still continues to show "no gd"
What if I reset all the parameters of the camera?