Question regarding RAM upgrade:

I have a MacBook Pro (Early '08) 2.4GHz and tried to upgrade to 4GB. I bought Kingston KVR667D2S5/2G x 2 sticks.
The funny part is I can't boot up (screen blank) with either stick individually or paired. But it works fine if I put the existing 1GB + new KVR667D2S5.
Can anyone tell me what is the issue? I read somewhere that MBP prefers kingston certified RAM, I think the code is MB.. something.
But I was browsing thru forums and saw number of people had no problems with this ram model?

Thanks.

This post has been edited by jeravius: Jun 21 2009, 10:36 PM