Don't enter anything in the "Enter Amount" box for Box 20, Code Z-Other Information (see the attached sample screen, Box 20, Code Z)
Select "Continue".
The next screen will give you plenty of options for entering the Z1 to Z6 amounts. If the description isn't already displayed, you can type them in at the bottom. Don't enter "zeroes" or Codes with an amount of "zero".
Run out of lines at the bottom? Just press "Tab" key and a new line appears (see attached sample screen, Box 20, Code Z Amounts).
