Ram only fits into 1/4 slots in thinkpad W520

I'm having an extremely strange problem. I just bought two identical sticks of Corsair 8GB DDR3 ram to put into my thinkpad W520. I had no problem whatsoever replacing the existing 4GB stick of ram in the slot under the keyboard. However, the other stick of ram will not fit into any of the other slots, neither the other one under the keyboard, nor the two under the laptop! Neither the new stick nor the old stick which I replaced will fit into any of these three slots, no matter what angle I try to insert them from, nor how hard I push. What should be as easy as this:

Lenovo ThinkPad W510 RAM Installation Guide - YouTube

simply does not work. To be clear, the notch lines up and everything, it's just impossible to get the stick of ram to actually be inserted into any of these slots, whereas it fits perfectly in the one slot under the keyboard. Am I missing something? Is there some component that I need to remove? I've searched around and no one seems to have had any sort of similar problem. Also, apparently some W520s have "dummy ram" sticks inserted into two of the slots, but this is certainly not the case in my model, and regardless, at least one of the three now-open slots should work. If anyone has any ideas please let me know, thanks in advance.

 

That is very odd. Can you take some pictures showing how it doesn't work? Are there any stickers that are in the way of the connection slots?

 

That's very weird indeed... Usually all you have to do is insert it at an angle (with notches lined up) and push flat until it clicks into place. Maybe the RAM stick is misformed, perhaps?