Start from offset

[Charles Johnson]

get_iplayer --mode=flashaaclow1 --flvstreamer=/usr/local/bin/rtmpdump 
--start $((120*60)) --get 10480

is what i attempted (start two hours in from start of the programme). I get

INFO: Connected...
ERROR: RTMP_ReadPacket, failed to read RTMP packet header
INFO: Command exit code 1 (raw code = 256)
WARNING: Failed to stream file 
/tmp/Breakfast_-_Friday_-_Sara-Mohr_Pietsch_b01mny7n_default.partial.aac.flv 
via RTMP
INFO: skipping flashaaclow1 mode
ERROR: Failed to record 'Breakfast - Friday - Sara-Mohr Pietsch (b01mny7n)'

Is this an incorrect invocation or is it simply that the offset is 
unsupported?

CJ