I'm not an expert, but here are some comments.
1) Perhaps your dependent or someone else already filed a return for them?
2) Double check the personal information you entered for your dependent's return. Be sure that the box labeled I can be claimed as someone's dependent is checked.
See: https://ttlc.intuit.com/community/taxes/discussion/where-do-i-enter-i-can-be-claimed-as-a-dependent/...
3) It looks like you are using the desktop version of Turbotax, which allows for multiple e-filings
https://turbotax.intuit.com/personal-taxes/compare/desktop/
4) It may be possible that your dependent is a victim of fraud.
