Martijn,
I was having a similar (perhaps, the same) problem. I have a classified
satellite image and I need to generate a black-and-white map for
publication. I defined and set patterns and set colors to black and
white. The black-and-white map is generated just fine, with all the
correct patterns. But, I don't get a legend out along with the map.
Are you at least producing a legend only in the wrong location?