Best build for invisible stealth?

Currently have one ☆ Chameleon and five ☆☆☆ Secret agent plus all the relevant maxed perk cards on Agility (sneak and so on). Also have a Civil engineer armor so no heavy armor. But still enemies can sense me when somewhat near. What can I do to truly be totally invisible (when standing still of course) and not noticed?

The chinese stealth armor makes no difference from what I can tell so I am missing something, or is it not possible?