TSearch: Need debug help

SELECT ts_debug('durst');
(default_german,lword,"Latin word",durst,"{de_ispell,de}","'dur' 'sen'")

SELECT ts_debug('höchsten');
(default_german,word,Word,höchsten,"{de_ispell,de}","'sen' 'höch'
'höchst' 'höchsten'")

For some reason both produce the lexem 'sen'. That leads to strange
results. Search for `durst' will highlight `höchsten' with headline().

Server is PG 8.0.4,
german snowball stemmer,
dictionary used is http://hannes.imos.net/german_iso.med
(From OpenOffice)

What causes some words to result in `sen', though they don't contain
that lexem?

Thanks!

--
Regards,
Hannes Dorbath