To file a State return separate, your Federal return must be accepted. You can file both a Federal & State returns at the same time but not all State forms are available yet to e-file.
You can file a Federal & State separately. Although state returns can be e-filed with your federal return (or after your federal return has already been accepted), it's no longer possible to e-file state returns before the federal. They are taking this measure to add an extra layer of security to all e-filed state returns.