different multicast woes

[Lloyd Wood <L.Wood@surrey.ac.uk>]

Running either ns 2.1b3 or a recent snapshot on this:

My simple multicast simulation script (okay, on top of a fairly
complex mesh topology) happily parses all the
construct-a-simple-multicast-tree Tcl (liberally copied from
tcl/ex/newmcast/cmcast-100.tcl, too...)  without error; it's after
that the fun begins.

I'd appreciate it if someone could at least provide
some debugging tips, as what this implies and how to rectify it is a
little beyond me at present: 

ns: _o4446 start: 
    (_o4446 cmd line 1)
    invoked from within
"_o4446 cmd start"
    invoked from within
"if [catch "$self cmd $args" ret] {
set cls [$self info class]
global errorInfo
set savedInfo $errorInfo
error "error when calling class $cls: $args" $..."
    (procedure "_o4446" line 2)
    (SplitObject unknown line 2)
    invoked from within
"_o4446 start"

rerunning and stepping through with tcl-debug active says:

1: $ns at 1.0 "$n(5) join-group $m0 $group"
dbg1.2> n
1: $ns at 7.0 "finish"
dbg1.3> n
1: $ns run
dbg1.4> n
total = 132
5: _o4 run-mcast
dbg5.5> n
5: _o4446 start
dbg5.6> n
5: tkerror {ns: _o4446 start}
dbg5.7> n
ns: _o4446 start: 
    (_o4446 cmd line 1)
    invoked from within
"_o4446 cmd start"
    invoked from within
"if [catch "$self cmd $args" ret] {
set cls [$self info class]
global errorInfo
set savedInfo $errorInfo
error "error when calling class $cls: $args" $..."
    (procedure "_o4446" line 2)
    (SplitObject unknown line 2)
    invoked from within
"_o4446 start"

A tkerror? It's always in SplitObject, too.

I'm stumped. Suggestions?

thanks,

L.

<http://www.ee.surrey.ac.uk/Personal/L.Wood/>PGP<L.Wood@surrey.ac.uk>