Did you e-file the Federal return, and has it been accepted?  You won't be able to e-file a state return until the Federal is accepted.   If you mailed the Federal return, you cannot e-file the state return.

Here's how to open your return back up:      Hope this helps.....

• You can log in and go to your 2015 Tax Timeline.  Scroll down to "Some things you can do" and click "Add a State."
• That won't really add an additional state, it will just open your return back up.
• Then once the return is open you can go to the State Taxes tab to complete your state return.
  

NOTE:  Do NOT use this method to open a return to make changes to an already-filed return.   If you later need to make changes, you have to go through the formal amending process, and your return must start off exactly as originally filed.