[ns] multicast Monitor Configuration

[Anastasia Katranidou]

Hi,
Does anyone know how I can configure the multicast monitor in order to see
information of the packet activity?
I added the following lines as it is mentioned in ns-manual:

set mcastmonitor [new McastMonitor]
set chan [open cbr.tr w]   # open trace file;
$mmonitor attach $chan     # attach trace file to McastMoniotor object;
$mcastmonitor set period_ 0.02         # default 0.03 (sec);
$mmonitor trace-topo                    # trace entire topology;
$mmonitor filter Common ptype_ $ptype(cbr) # filter on ptype_ in Common header;
$mmonitor filter IP dst_ $group # AND filter on dst_ address in IP header;
$mmonitor print-trace  # begin dumping periodic traces to specified files;

,but there is the folowing error message:

wrong # args: should be "set varName ?newValue?"
    while executing
"set chan [open cbr.tr w] # open trace file"
    (file "ex-mcast.tcl" line 16)

Did anyone implemented the multicast monitor with success in order to help
me?

Thanks in advance,
Anastasia Katranidou