I just upgraded the RAM in my iMac, so I decided to take the two 512MB sticks out of it and replace the RAM in my MacBook(currently 2 256MB sticks). The RAM worked great in my iMac, but for some reason, the MacBook can't see one of the sticks at all, no matter what slot it's in. Is there any reason it wouldn't work in the MacBook, but would in the iMac, and is there any way to fix it?