Dell vostro 1500 RAM upgrade unsuccessful

Hi

I have a Dell Vostro 1500 ..It came with default 2 Nos of 512 MB DDDR2 RAM 667 Mhz from the factory. The memory make is "Hynix"

I bought 2 GB DDR2 Transcend 667 Mhz,,(single chip)

One of the RAM slot is located at the base of the laptop (which is sort of easier to access) ..The other slot is located underneath the keyboard , wherein you have to ply the plastic case open , take out he keyboard panel and then change the RAM.. I thought that anyway since this is a single bar , I might as well replace it with the RAM from the base of the laptop...

I have installed as instructed ( There is nothing special apart from pushing the knob, taking out the old and inserting the new one)

Initially , the "A" (caps lock) indicator on top left corner was blinking on and off. I read that you have to reseat the chip and I did that..

On boot , BIOS gave a message that the memory settings might have changed press f1 to continue or f2 to run setup.. I clicked F1 and it loaded.
The problem now I find is that the 2GB is not at all recognized ...CMOS is showing 512 MB RAM when it should be 2.5 GB

PL help!