It's quite easy. I have two computers and one server where the images are stored. On the first computer (mini mac) I marked a huge amout of images with keywords. On the mini mac I can search and will find the pictures I wanted. Importing and using the same set of keywords on the macbook pro the search doesn't find anything and if I open one of the marked pictures, on the macbook it appears with no stored keyword at all. If I open it on the mini mac the keywords ate shown. Strange, isn't it?