PNY memory upgrade for MacBook

[Jsaaz2]

I just purchased (2) 2GB PNY PC-5300 memory sticks for my black Macbook but when I install both 2GB stick my MacBook will not boot but when I install (1) 1GB and (1) 2GB it boots up fine with a total of 3GB listed in the About This Mac and it doesn't matter what combo I try with the sticks. The 3GB works but the 4GB does not. Any answers as to why would be great.

 

[Eidorian]

Which model of the MacBook? More information on the specifications are needed.