My youngest son wasn’t included on my earned income credit and I was wondering if it was a mistake? He was born 12/12/2018 and my other two sons were counted.

My other two sons are 3 and 2. I filled everything on the app and that’s why I’m confused because the paperwork says you can have a maximum of 3 children on the Earned Income Credit. His information is on the other tax forms but he was left out on the Earned Income Credit.