Memory in weasel

The documentation for my motherboard is pretty clear about how it can take up to 4GB except for the fact that it only sees 3GB out of four.

And it says that you must fill the green slots first and then the purple slots. But when I put a simm in each green slot, it only sees one of them. One I have a simm in the first two slots (one green, one purple) it sees 2GB. When I have a simm in each of the four slots, it sees 3GB.

I've been running most of the time with 2GB, one simm in a green and one simm in a purple.