[ns] "can't read "node_(1)": no such variable"

[Pragasen Mudali]

I am using ns-allinone-2.29 and successfully generated both the scenario and
the connection pattern files using the Monarch project's extensions which
are included in the distribution.

Running the .tcl script generated the error message below. It seems that the
node_(1) object has not yet been created. Is this because the scenario file
has not been processed yet? If so how do I ensure that the scenario file is
processed before the connection pattern file?

num_nodes is set 30
Loading connection pattern...
can't read "node_(1)": no such variable
    while executing
"$ns_ attach-agent $node_(1) $udp_(0)"
    (file "cbr-30-20-4-64" line 8)
    invoked from within
"source.orig cbr-30-20-4-64"
    ("uplevel" body line 1)
    invoked from within
"uplevel source.orig [list $fileName]"
    invoked from within
"if [$instance_ is_http_url $fileName] {
set buffer [$instance_ read_url $fileName]
uplevel eval $buffer
} else {
uplevel source.orig [list $fileName]
..."
    (procedure "source" line 8)
    invoked from within
"source $opt(cp)"
    invoked from within
"if { $opt(cp) == "" } {
        puts "*** NOTE: no connection pattern specified."
        set opt(cp) "none"
} else {
        puts "Loading connection pattern..."
        ..."
    (file "wireless.tcl" line 257)

All help is appreciated

P Mudali