fontset named ‘book-fonts’

heyho everybody!

I took generate_image.py and osm.xml from http://svn.openstreetmap.org/applications/rendering/mapnik/

when trying to compile I get the following ERROR:

Traceback (most recent call last):
  File "C:\0A\9\run_python.py", line 3, in <module>
    execfile(r"C:\0A\9\generate_image.py")
  File "C:\0A\9\generate_image.py", line 42, in <module>
    mapnik.load_map(m,mapfile)
RuntimeError: Unable to find any fontset named 'book-fonts' in TextSymbolizer in style 'area-text' in map 'osm.xml'

Can someone please tell me, what I might have done wrong? Would be very kind! Thanks!

Greetings Matze