1.8V Memory Stick usage

I have a Kingston KVR667D2E5K2/2G 1.8V memory stick.
When I put it into a HP a601on PC it will not work. It just
gives a series of beeps. When I put another computer it only
shows 1G in the windows system properties.
Could some tell me why this stick is not working in my
HP a601?

I think this is a DDR 2 two gig stick but could be work.

Thank you,