Create Apple ID for a child - Invalid Security Code

I am trying to set up an apple ID for my child. I am using my phone and completing the steps through Family Sharing under the Apple ID on my phone. When I get to the step to enter the verification code I get the code to pop up in front of me on my phone and I enter it and each time I get the error "Cannot Complete Action - Invalid Security Code".

What is happening? How do I fix this?