heat sink dont fit

i have just bought a volcano 9 heat/sink for my amd 2200xp.
first it was a barstard to put on. <had to dismantle it first> but when it was finaly on the temps rose by 10c. so i thought i had not put it on properly or put on to much artic paste. so took it off <pure hassel> reapplied the paste put it buck on properly and the processer failed!!!! 3 times.!!!!! put back on the old sink and it worked fine. om examining the heat sink i noticed that the `step` which only allows you to put it on one way?? was much bigger than the one on my old heat sink. there fore the heat sink is not going to cover the processer properly. can any one tell me whats going on? as it says that the volcano 9 was suitable for AMD athlon XP up to 2600 and iam using 2200. so what the f**k is going on. i fitted it properly and when i refitted it the same way it wouldnt work at all. iam going to send it back of course, but i thought i would run it buy you guys first.
any comments any one??????????????????????????