How to check the topology generated by gt-itm?

[K Sun <ksun@essex.ac.uk>]

Hi,
   I am a beginer of ns programming. Recently, I am trying gt-itm (the 
topology generator). 
   My problem is I could not check whether I have got a correct 
topology. I use "sgb2ns" to translate "r100-0.gb" (under the 
sample-graphs directory) into r100-0.tcl. It seems there is no problem 
with this r100-0.tcl. Then, I try to use "nam" to see this topology 
directly. (I do not know whether there is other ways to check that 
topology except using nam.) I add:


	set ns [new Simulator]

	set nf [open out.nam w]
	$ns namtrace-all $nf


	proc finish { } {
		global ns nf
		$ns flush-trace
		close $nf
		exec nam out.nam &
		exit 0
	}

	$ns at 1.0 "finish"

	$ns run

to the file, r100-0.tcl, and run "ns r100-0.tcl".
However, there is nothing displayed by "nam".
The content of "out.nam" is:

V -t * -v 1.0a5 -a 0
A -t * -n 1 -p 0 -o 255 -c 15 -a 1
A -t * -h 1 -m 127 -s 8

Perhaps, I could not make correction on the .tcl file like this way.

Who can tell me why I get such a result and how to check the topology 
generated by gt-itm in a directly way?

Many thanks,

Sun Kai