Schedule3 is used when there are Additional Credits and Payments to be entered on your tax return.
Look at your Schedule 3, on what line(s) of the Schedule are you seeing an amount entered?
You can view your Form 1040 plus Schedules 1, 2 and 3 at any time using the online editions. Click on Tax Tools on the left side of the online program screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.