The Form 1099-R does not have a box 14a.
It has Box 14 - State tax withheld, Box 15 - State. Box 15 - State number. Box 16 - State distribution
Box 16 can be the same amount that is in box 1.
If you are getting an error for box 16 no matter what is entered, then delete the Form 1099-R and re-enter manually.
