It sounds like your case was not dismissed for lack of evidence, but was dismissed due to an expungment action after a conviction. If this is the case, the President's order requires no criminal history. There have no case law established yet if that excludes juvenile records. Additionly, since this is an executive policy, there really would be no judicial oversight. Sorry, but it does not appear to be very good news for you. Good luck.
Expungements will be dealt with on a case by case basis. It does not bar you from applying - but you will need to turn in a thorough application with lots of evidence. I would recommend speaking to a lawyer.
Best of luck,
Sanjay A. Paul, Esq.
This is not legal advice. No attorney client relationship exists between us.