Google Desktop Search misses many of my Word files

I use Word 2002. When I type in the exact sentence from a file and try
to search for it via Google Desktop search, it often won't locate it. I
even added the exact directory some of the files were located in, and
it still didn't work. The files aren't that long. They've all been
created within the past six months. What's going on? Anybody know?
Anything to do with sharing? (I am hooked up with another computer in
my home.)