If he knows you (and your email address) he will respond. Otherwise he will not. There is still a lot of oversight there for what he does, and he is extremely careful about what he writes or who he writes it to.
Best to call him and discuss over the phone, even better if you have at least met him once and jog his memory.
He's getting your emails, he just may not know who is sending it. Skype his cell, he answers any hour of the day, so be mindful of the time over there.
Carry on......