You probably haven't ever had an Employer ID on your DFAS Form W-2 (I haven't). This post explains what to do if there is no employers State ID on your Form W-2: No employers State ID number on Form W-2, Box 15?
If this doesn't resolve the error, you may have to delete the Form W-2 using the Delete a Form tool and then re-enter it in the Form W-2 interview.
See: How do I delete forms in TurboTax Online?
After deleting the W-2, log out of the program. When you log back in, you use the Delete a Form tool to see if the W-2 has been removed from the list of forms in your return.
If the delete and re-enter process does not allow you to correct the problem, you may have to try Using Clear & Start Over in TurboTax Online
