granularity doesn work as expected

[Folllast]

I want to reduce the filesize for a very big Map. I want to use the "granularity"-Tag in the --write-pbf Command. But always when i use an other value than "100" the file in Maperitive seems to be empty. the Filesize is almost the same Size as the read-file.
I use this command:

osmosis --read-pbf file="highway2_05.osm.pbf" --write-pbf granularity=10000 file="highway3.osm.pbf"