Make-Lan fail

["Wee Ching Wi" <eng50527@leonis.nus.edu.sg>]

Hi,

TO creat a simple LAN, on ns 2.1b2
I used :

$ns make-lan "$n1 $n2" 10Mb 10ms LL Queue/DropTail Mac/Csma/Cd

but I have an error message from executing make-lan command :

Can't read "$namtraceAllFile_ variable does not exist"

Anyone can help me? If you have a working example on LAN, it will be very
helpful.

Thanks.