Tax form requires W-2 box 12d, but box is blank. How do I proceed?

[TeresaM]

If you need to enter a Code D for the amount in Box 12, there should be a little triangle pointing down, to the right of Select a Letter Code. If you click on the triangle, it will drop down a menu. 
 

If you need to enter another Code for Box 12, there is a plus sign in blue and it says Add another box 12 item.