error in tcl file

 when i am  trying to generate  nam  file  it
  gives  error :   "Flow 1 starts at time 0.000000
                        Segmentation fault (core dumped)"


plz give me solution how to solve this  problem


--------------------------------mkc.tcl---------------------------------------------------

# create scheduler
set ns [new Simulator]


set f [open out.tr w]
$ns trace-all $f
set nf [open out.nam w]
$ns namtrace-all $nf
# turn tracing on
#set ns_f [open HeteroFlow.tr w]
#$ns trace-all $ns_f

#set stat [open stat.txt w]

#create topology

#set number of flows
set N 2

#set the output file
for {set i 1} {$i<=$N} {incr i} {
	set out_($i) [open out$i.txt w]
}

#source
for {set i 1} {$i<=$N} {incr i} {
	set R_($i) [$ns node]
}

#bottleneck
set R_([expr $N + 1]) [$ns node]

#sink
set R_([expr $N + 2]) [$ns node]

#create the link connecting the source and sink
for {set i 1} {$i<=$N} {incr i} {
		$ns duplex-link $R_($i) $R_([expr $N + 1]) 500Mb [expr 100 + [expr
$i - 1] * 900]ms MKCQueue
}

$ns duplex-link $R_([expr $N + 1]) $R_([expr $N + 2]) 10Mb 10ms MKCQueue

for {set i 1} {$i<=$N} {incr i} {
		set mkcq_($i) [[$ns link $R_($i) $R_([expr $N + 1])] queue]
}

set mkcq_([expr $N + 1]) [[$ns link $R_([expr $N + 1]) $R_([expr $N +
2])] queue]

# link capacity
for {set i 1} {$i<=$N} {incr i} {
		$mkcq_($i) set C 500000000
		# the router sampling interval
		#$mkcq_($i) set T 0.1
		$mkcq_($i) set T [expr 0.1 * [expr $i - 1]]
		$mkcq_($i) set rid $i
}

# the bottleneck link capacity
$mkcq_([expr $N + 1]) set C 10000000
# the router sampling interval
$mkcq_([expr $N + 1]) set T 0.1
$mkcq_([expr $N + 1]) set rid [expr $N + 1]


#create and attach MKC agent

for {set i 1} {$i<=$N} {incr i} {
	# create a new MKC sender
 	set Src_($i) [new Agent/MKC]
	
 	# attach the sender at the source node
	$ns attach-agent $R_($i) $Src_($i)

 	$Src_($i) set alpha_ 1000000
	$Src_($i) set beta_ 0.5
	$Src_($i) set fid_ $i

	# set the initial rate
	$Src_($i) set init_rate_ 100000
	
	# set the data packet size
	$Src_($i) set packetSize_ 200
}

#create and attach MKCSink agents

for {set i 1} {$i<=$N} {incr i} {
	set Snk_($i) [new Agent/MKCSink]

	# set ACK packet size
	$Snk_($i) set packetSize_ 40

	# attach the receiver at the sink node
	$ns attach-agent $R_([expr $N + 2]) $Snk_($i)
}


# connect each pair of sender and receiver

for {set i 1} {$i<=$N} {incr i} {
	$ns connect $Src_($i) $Snk_($i)
}

# schedule the events

$ns at 0 "$Src_(1) start"
$ns at 5 "$Src_(2) start"

for {set i 1} {$i<=$N} {incr i} {
	$ns at 0 "record $Src_($i) $out_($i)"
}


for {set i 1} {$i<=$N} {incr i} {
	$ns at 100.0 "$Src_($i) stop"
}

$ns at 100.0 "finish"

proc record {mkcsrc file} {
        global ns f nf
	set step 0.1
    	set now [$ns now]
	set rate_ [$mkcsrc set rate_]
    	set pkt_loss_ [$mkcsrc set pkt_loss_]
    	puts $file "$now $rate_ $pkt_loss_"
    	$ns at [expr $now+$step] "record $mkcsrc $file"
}

proc finish {} {
        global ns f nf

        $ns flush-trace
        close $f
        close $nf

        puts "running nam...."
        exec nam out.nam &

        #exec xgraph out0.tr out1.tr out2.tr -geometry 800x400 &
	exit 0
}

$ns run





thank you