to upgrade the RAM of an Acer Aspire 5024wlmi from 1 to 2gb

Hi. I'm trying to upgrade the RAM of my Acer Aspire 5024wlmi from 1 to 2gb. I have bought a couple of KomputerBay 1gb RAM  compatible models with the Acer RAM specifications (DDR SODIMM (200 pin) 333Mhz PC2700 DDR333 CL2.5).

After the replacement of the two 512mb RAM, the computer starts up, you can hear just two "beeps" but the screen remains totally black, nothing else.

Besides replacing the RAM, I must make something else that I don't know?

Thanks for the help