How do I reset the back pin asked for when changing lock screen options?

[AC Question]

I somehow managed to change my device lock screen from a pattern to nothing. I am attempting to change it back. However, when I go to setting, lock screen, screen lock, it asks for confirm pin. Here is where I am stuck. I have tried every combination I can possibly imagine and nothing is working. I have attached a picture of what I am seeing. Can anyone help me reset this pin?

 

[belodion]

I expect it's asking for the backup PIN that you set when you set up a pattern lock.