I have a MacBook Pro Mid-2009 with 2GB of RAM (1xGB). I had recently decided to upgrade it to 8GB after checking the allowed capacity on Apple support website. I ordered 2x4GB of 1066GHz RAM and installed both the RAM sticks. The machine did not boot with continuous 3 beeps. I removed the RAM sticks and installed them with 1x1GB of the old stick and it works fine. (So a total of 5GB). I have tested this combination at both the slots with both the new 4GB RAM sticks. They work fine with the 1GB stick. However they do not work together. Both the sticks are exact same model, I bought them together. Is there something I am missing or doing incorrectly?