key param doesn't work with reducing views

I have a reducing view which has date-based keys (["2010"] or ["2010", "09"] or ["2010", "09", "07"]).

reduce=true&group_level=2&startkey=["2010","09"]&limit=1 gives me {"rows":[{"key":["2010","09"],"value":

]}.
reduce=true&group_level=2&key=["2010", "09"] gives me

.

This seems wrong.