Are you claiming him on your return? Go back to My Info and check his entries like birthdate. Are you sure you don't have the 600 on 1040 line 30? You entered 2900 and 1200 in the 2 boxes?
Before filing, You can preview the 1040 or print the whole return
https://ttlc.intuit.com/community/accessing/help/how-do-i-preview-my-turbotax-online-return-before-f...
