If there is a 0 (zero) entered in box 7 of the Form 1099-R, you will have to contact the plan administrator to get a corrected Form 1099-R. There is no such code 0 for box 7.
Look again at the Form 1099-R. It's doubtful that box 7 actually has a zero in it because no payer would ever have a reason to put a zero in box 7. Perhaps there is a 7 in box 7.