Need to add line to distributions, but can not due to distributions being protected

 Hello,

I am having trouble in Oracle R12. I am trying to add a line in payables distribution, but all the fields are protected and I cannot add a line at the bottom to add in the entry. When I press the down arrow key to add an entry, it tells me "FRM-41051: You cannot create records". I need to add a line in order for the invoice and distribution total to match. Because this and two other lines are out of balance, the validation process will not validate. How can I add a line or fix this issue? Please let