Nodes and links creation within a procedure

Hello everyone,I am new to ns2. I am trying to create nodes and links within a procedure, and call this procedure during run time. I am able to create the specified nodes and links within the procedure. The main issue is that trace files are not being updated after using flush-trace command. The code which i am usingset ns [new Simulator]set tracef [open "trace.tr" w]set namtracef [open "namtrace.nam" w]$ns trace-all $tracef$ns namtrace-all $namtracefproc finish {} {global ns namtracef tracef$ns flush-traceclose $namtracefclose $tracefexec nam namtrace.nam &exit 0}proc createTopology { } {global nsfor {set i 0} { $i < 7} { incr i } {	 set n($i) [$ns node] 	  } for {set i 0} {$i < 7} {incr i} {  $ns duplex-link $n($i) $n([expr ($i+1)%7]) 1Mb 10ms DropTail}}$ns at 0.5 "createTopology"$ns at 
 5 "finish"$ns runThe output of namtrace.nam file :V -t * -v 1.0a5 -a 0A -t * -n 1 -p 0 -o 0x7fffffff -c 30 -a 1A -t * -h 1 -m 1073741823 -s 0I am not sure what the mistake is. Thanks.Srikan!
 th