[ns] multi-channel question

[wjw7869]

Dear Ram¨®n Ag¨¹ero Calvo and all,
 I modified ns2 code to support multiple interface according  Ram¨®n 
Ag¨¹ero Calvo 's Document, but when i run script_ ,I meet following 
errors,I do not konw how to debug error in  ns2 ? anyone could help me solve 
this problem ,I am very appreciate of you!
 
 num_nodes is set 50
INITIALIZE THE LIST xListHead
can't read "tracefd": no such variable
    while executing
"if { $tracefd == "" } {<BR>return ""<BR>}"
    (procedure "cmu-trace" line 4)
    invoked from within
"cmu-trace Send "RTR" $self"
    (procedure "_o17" line 35)
    (Node/MobileNode add-target-rtagent line 35)
    invoked from within
"$self add-target-rtagent $agent $port"
    (procedure "_o17" line 29)
    (Node/MobileNode add-target line 29)
    invoked from within
"$self add-target $agent $port"
    (procedure "_o17" line 15)
    (Node attach line 15)
    invoked from within
"$node attach $ragent [Node set rtagent_port_]"
    (procedure "_o3" line 78)
    (Simulator create-wireless-node line 78)
    invoked from within
"_o3 create-wireless-node"
    ("eval" body line 1)
    invoked from within
"eval $self create-wireless-node $args"
    (procedure "_o3" line 23)
    (Simulator node line 23)
    invoked from within
"$ns_ node"
    ("for" body line 2)
    invoked from within
"for { set i 0} { $i < $val(nn) } {incr i} {<BR> set node_($i) [$ns_ 
node]<BR>#set rt($i) [$node_($i) agent 255]<BR>#$rt($i) set-mac [$node_($i) set 
mac_(0)]<BR>$n..."
    (file "channel.tcl" line 82)
 
 
 



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