Reducer with 7z enabled does not work.

[electroteque]

Added 7z to the bin path, tried the command line and ant task and both
display 0% compression

[DEBUG] Waiting for 7z to finish.
[INFO] Compression ratio: 0.00%
[INFO] Total bytes: 0
[INFO] Completed in 639ms.

7z disabled

[INFO] Apparat -- http://apparat.googlecode.com/
[INFO] Launching tool: Reducer
[INFO] Compression ratio: -5.41%
[INFO] Total bytes: -10673
[INFO] Completed in 252ms.


ant output

[reducer] [INFO] Rebuilding constant pool ...
[reducer] [INFO] Rebuilding constant pool ...
[reducer] [INFO] Compression ratio: 0.00%
[reducer] [INFO] Total bytes: 0
[reducer] [INFO] Completed in 7901ms.



these are my options

-Dapparat.7z.enabled=true -Dapparat.7z.path=/usr/bin/7za -
Dapparat.debug=true

Any ideas ?