There's a box on form 1040, that must be checked, on the dependent's return, "Someone can claim you ....as a dependent".
In TurboTax, he indicates that somebody else can claim him as a dependent, at the personal information section. TT will check that box on form 1040.
Failure to check that box is the most likely cause of your problem. You will have to file a paper return, claiming your dependents. In the meantime, the dependent needs to file an amended return unclaiming himself. You do not need to wait for the dependent to file an amended return to file your return. The IRS will process your paper return and send your refund.
