iMac RAM upgrade help

Hi all, yes it's Christmas Day and I'm installing some RAM for my mac. I recently got 2 x 2GB 200-pin DDR2 SO-DIMM PC2 - 6400 CL6 RAM. When I install it and turn it on, it boots up and makes the whirs like it should, however I just get a black screen and nothing comes up. Any help would be greatly appreciated.

Did you use a Anti-Static Mat?

Are you sure your Mac takes that RAM?

Are you sure you properly seated the RAM?

Have you tried going back to having just the old RAM installed?

P

Try removing the RAM and insert it again but push fairly hard to make sure it is seated properly. I'd suggest doing this a few times just to get the feel for pushing a little harder each time.