Cpu cooler clamps wont fit!

There is a little lever on one side of the stock cooler, make sure it lifted up, clip the side without the lever on first, then lift the lever up, making it looser, now click the other side, and push the lever back down, it can be quite hard to push, but make sure its all the way down.
 
What cpu are you using? There should only be one side with a clamp. The other is just a simple metal cutout square which you hook onto the plastic hook on the heatsink. Make sure the lever on the otherside is point up, therefore loosens it.
 
Possibly? Maybe a bent clamp, or somewhere bent inbetween the two sides? I'd try getting someone to take a look at it in person who knows how to install them. (Not saying you do not know, but just to be on the safe side)