namtrace-all command not found

[iimene]

Hello,

when i'm trying the first example in ns
---------------------------
#Create a simulator object
set ns [new Simulator]
#Open the nam trace file
set nf [open out.nam w]
$ns namtrace-all $nf
----------------------------
it returns namtrace-all command not found

could you plz explain me why this happens

thanks in advance