[ns] can't read "chan": variable is array

[Fazlullah Khan]

Hi all!
While running the simulation I get the following error, any body have
any idea about it.
num_nodes is set 5
can't read "chan": variable is array
    while executing
"$node add-interface $chan $propInstance_ $llType_ $macType_
$ifqType_ $ifqlen_ $phyType_ $antType_ $topoInstance_  $inerrProc_
$outerrProc_ $FECProc_..."
    (procedure "_o3" line 69)
.....
    invoked from within
"for {set i 0 }  {$i < $val(nn) } { incr i } {
set node_($i)  [$ns_ node]              ; # usually problem comes here
set ragent_($i) [$node_($i) set ragent_]
set ..."



-- 
Regards
Fazlullah Khan