Problems with ns for win95

[Ahmed Elkousy <elkousy@usa.net>]

Hello,
I am a new user of NS. I downloaded the self-extracted ns binary code for
windows from the ns-build page.

When I type 'set ns [new simulator] ' , I get the following error message :
class simulator: constructor failed (Invalid command name "simulator")

Any hints on what my be the problem ? 

Regards and thank you very much.

Ahmed Elkousy