Dump threads not positive number

Hello,

Kernel: 2.6.29-rc6
LTTng: 0.103
ltt-cntrl: 0.66
lttv: 0.12.11-18022009
Target: x86


When running lttctl 
>lttctl -n trace -d -l /mnt/debugfs/ltt -t /tmp/trace

I get the error "Dump threads not positive number". Looking at the code
in lttctl.c sscanf is passed a string "optarg" (if the above command is
used contains "trace") and is converted to an unsigned int to be stored
in "opt_dump_threads" which is an unsigned int. I do not understand the
need to convert an arbitrary string and store its value into the
variable "opt_dump_threads"


Does anyone have the same problem and a solution? What is the meaning of
this error?

Thanks and regards,
Philby