US Immigration from Costa Rica

On input capable fields in the I-751 Form the entry of N/A and none isn't accepted. For example Part 1, question 9 will not accept none, giving a message to the effect that all positions must contain an entry. Part 1 question 13 will not accept N/A because only numbers are accepted for the date. It would appear that I should follow the for and make entries where I have information and leave the rest blank. I would like very much to hear what others have to say about this topic. Thanks Very Much for each and every response.