Velocity with fvcurve

Hi, I have midish running on a raspberry pi connected to a Yamaha player
piano via a USB midi cable.

I can successfully import a midi file and play, stop and pause playback of
the midi file to the piano.  So far, so good.

What I am now trying to do is change the output volume (velocity I believe)
as the piano is very loud at the default level.

I have tried setting a filter as follows, but there does not seem to be any
adjustment to the output.
----------------
dnew 0 "20:0" wo
fnew volume
fvcurve {} (-63)
import "/tmp/song.midi"
p
-----------------

I'm wondering if the filter is being applied to the input file at all?
Would appreciate any help.

Thanks so much!
-- 
Sent from my mobile.