"write data fail" get_key_data error

[Cylinder]

I am running smc_util under Linux on a A1312 EMC2309 (late 2009) as root. I did
rmmod applesmc
which did remove the applesmc module.
The first command in the tmd_on.sh script is
./SmcDumpKey MVHR 1
which then gives

type="flag" length=1 flags=c0
data="\x00"
target value: 01
send_byte(0x01, 0x0300) fail: 0x00
MVHR: write data fail
write_smc get_key_data error

And nothing happens. Any ideas? If not, I will start digging into the C code.
Thanks!