So I just finished the Nocturnal/ Nightingale quests and I chose the Agent of Subterfuge (I mean invisible sneaking?! Hellz yeah). After I got it I sneaked to see what it looked like, and I didn't go invisible. Then I saw a power (Agent of Shadows or something) and I used it, and it worked. But when the time ran out on it, I was still invisible when I sneaked, so that confused the heck out of me. Not only that, but when I activated a door, I could no longer be invisible when I sneak, and the power wouldn't work.

Basically, can someone explain how it works plz? I thought it would be a permenent "Prize" from Nocturnal, but guess not.

No one???

Perhaps this will help:

http://www.uesp.net/wiki/Skyrim:Darkness_Returns