[ns] please help me multi-channel multi-interface [ns-2.29]

[ByungJoon Oh]

Hello respect NS-users,

when I simulated followed this website: http://www.cse.msu.edu/~wangbo1/ns2/ (Bo Wang's website),
But, I got the error messages since implemented $ns twoflows-1channel.tcl:
invalid command name "if{0}{"
while executing
"if{[info exists channel2_]}{"
 (procedure "_o3" line 45)
 (Simulator node-config line 45)
 invoked from within
"$ns_ node-config -channel $chan_6_ \
                                 -channel2 $chan_1_ \
                                 - 
                                 -

please advice for me!!!
Thank you so much in advance.

Best regards,
ByungJoon Oh,