Upgrading an older machine

I have an old Gateway 500X that came with an original 256 MB of PC2100 RAM. I recently bought a new 1 GB stick of PC2700 because the memory selector on the Gateway website recommended it for my system. However, when I add the upgrade to the second slot, the system boots, but it only finds 32 MB of RAM which is less than when I only had the original stick of 256 MB. If I remove the original stick and replace it with the upgrade, the same thing occurs.

The system doesn't support dual channel so the memory doesn't have to be installed in pairs. Could it be that I truly needed PC2100 instead?

So even the new stick by itself only comes up as 32 mg? But Gateway reccomends this stick for your machine?

Not that particular brand but a 1 gig PC 2700?

Perhaps the brand you got is incompatible?

BIOS needs an update?

Vdimm correct?