[ns] tracing SCTP trafic

[sofia insat]

Hi,

I have to trace SCTP trafic
I have used this script but it didn't work :

set trace_ch [open trafic.sctp w]
$sctp0 set trace_all_oneline_ 1
$sctp0 trace cwnd_
$sctp0 attach $trace_ch

Do you have any idea ??
thanks