I've been hitting the powercleans hard lately. They are a great exercise and I've been making fantastic strength gains as I improve my form (maxed at 195 today). As Tagio said, most likely you are doing some upright rowing rather than using your full hip drive to explode on the secondary pull
While I agree with Tagio's description of the powerclean to a certain extent, I find that most of the power in the lift comes out of the hip drive of the secondary pull rather than the jumping or shrugging part of the motion. I'm certainly no expert as I just started them myself (with the help of a coach), but in the beginning I would be much more concerned with the hip and leg drive as opposed to shrugging the shoulders.
If you can find a reference somewhere on the internet regarding proper setup, I believe that was the single most helpful thing in increasing weight when I was starting. Grip the bar wider than shoulder width, shoulders above the bar, flare the lats, and make sure you sit back a little bit. It's much different than the deadlift setup, although it may appear similar.