ns2 (tcl problem)

[rohit b k]

Hi,
i was writing a simple tcl script..

and i wrote these lines toorient the links between nodes..

 $ns duplex-link-op $n1 $n3 orient right-down
 $ns duplex-link-op $n2 $n3 orient right-up
 $ns duplex-link-op $n3 $n4 orient right
 $ns duplex-link-op $n4 $n5 orient right-down

but i am getting error message when i try to compile it..

 can't read "link_(0:2)": no such element in array
        while executing
"eval $link_([$n1 id]:[$n2 id]) $op $args"

    (Simulator duplex-link-op line 3)
    invoked from within
"$ns duplex-link-op $n1 $n3 orient right-down"
    (file "try2.tcl" line 34)

please help me...

thanks..