[ns] Tcl error

[Sven Ostring <ostrinsa@elec.canterbury.ac.nz>]

I'm getting the following error message regarding assigning to a RED 
queue the early drop target - this occurs inside my procedure 
Simulator instproc build-flow-monitor {} { } which I have successfully 
used in other simulations.  The Tcl error message hasn't been 
particularly helpful for debugging purposes - where's the problem likely 
to be occuring?

Thanks,
Sven.


    (_o482 cmd line 1)
    invoked from within
"_o482 cmd early-drop-target _o521"
    invoked from within
"catch "$self cmd $args" ret"
    (procedure "_o482" line 2)
    (SplitObject unknown line 2)
    invoked from within
"[$lnk queue] early-drop-target $edsnoop"
    (procedure "_o3" line 9)
    (Simulator attach-fmon line 9)
    invoked from within
"$self attach-fmon [$self link $node1 $node2] $flowmon $edFlag"
    (procedure "_o3" line 3)
    (Simulator build-flow-monitor line 3)
    invoked from within
"$ns build-flow-monitor $Node($centre) $Node($down) $edflag $fFlow"
    (procedure "build-topology" line 69)
    invoked from within
"build-topology $lnkType $numLinks $start $stop"