Please see the instructions in the TurboTax FAQ below on how to e-file your state after your Federal has already been submitted: How do I e-file my state after I already filed my federal?
If you continue to have this issue, it may be that you did not Transmit your Federal return. To check this, click here to ensure your e-filing was completed. If you find your Federal return was not submitted, you can follow the instructions here to complete it. You would be able to submit your federal and state together if this is the case.