Welcome to LQ.
I have followed the procedure
Looks like a faulty procedure.
The mentioned command is bad advice. And wrong.
This is what you should do :
$ cd ns-allinone-2.33/ns-2.33/
$ sudo make install ('make install' will copy 'ns' to /usr/local/bin/)
Make a backup : $ cp ns ns233-orig
$ sudo cp ns233-orig /usr/local/bin/
.. Then you still have an original 'ns*',
if you make any changes to ns-2.33/.
I.e. default simulations may require "ns-orig".
About "procedure´s" you can find on the Internet :
Remember that most of those tutorials are written by young students.
Who are using ns2 and a `Linux OS´ for the first time.