Did you leave them blank or did you enter $0? If you entered 0, you will need to remove the 0 and leave them blank. If you do not have a number in box 16 or if you have a 0 in box 16, you do not need to enter anything in the box.
However, depending on the state you live in this may be taxable income. If it is considered taxable income, then you can enter the amount that is in box 1 in box 16.
By placing a $0 dollars or leaving field 16 blank, the turbotax program would (still) not let me efile my tax return. Something still had to go into the field 16. it seems like using field 1 or field 2a of my W2 would work, but I do not know if that is the right answer or not.
The box 2a amount is the normal amount needed...as long as box 2a has a non-zero value in it, or is not blank.
Some states used to not require a value there, but some changes by some of the states, as to how they tax retirement income, or perhaps new state partial exemptions to some of your retirement income...those changes have generally required an amount to be put into box 16.