Memory problems with presario 4504

I am working on a Compaq presario 4504. I have installed a 32mb chip in the single dimm slot. It has 16mb on board. When I reboot the pc it only acknowledges 24mb of ram. I took it out and installed a 16mb chip and it found the full 32. I checked the documentation on the pc and it says the 32mb chip will work. I was wondering if anyone else has had this problem. I have heard of one other person, when I asked how it was fixed they couldn’t remember. ANy help would be appreciated.