New RAM unrecognized

I friend was dismantling a machine and gave me a 128MB PC100 stick. I tried to put it in my machine but my computer wouldn't recognize the new RAM. There are 3 slots- if the new RAM was in slot 2, only the RAM in slot 1 would take. If the new RAM was in slot 3, only 1 & 2 would take. If the new Ram was in slot 1, well... you get the picture. Any ideas why this would happen? All the rest of my RAM is PC100 too.

hmm

1st off im going to give you some my ideas, but there are alot of other people who are more experienced than me in this forum..

1, what operating system, and what mb are you using?

if you are trying to load up all three slots it could be a voltage problem, and IF you are using win98 there is a mereory limit i believe at 512mb of ram (but in my iwill kk266 it would not let me recognize any more than 256mb and I tried new everything.i got the memory utility "cacheman" and it worked and i still have no idea what caused it)

2. try using a utility "cacheman" , that helped me its a memory utility

3. it could also be a problem with trying to load up all three memory slots

4. could be bad ram

there are just merely some ideas but provide some more info about your system in the future so that way more people can help you out

Thanks! I'm running Windows 2000 Pro, trying to add the new stick bringing the RAM to 288. The RAM worked in the machine it had been in, also running W2K Pro. I tried just using 256 MB but it would only recognize my original 128 stick not the new one