[ns] NS New user. 'Error when calling class OldSim: example1a.tcl' sh own when trying to execute a script - URGENT PLEASE HELP!

[Bird, Kenneth]

Hi there,

I am a new user to NS and I am using the NS-2.27 all in one version on
Redhat Linux.  I installed it and validated it successfully.  However, when
I try to execute an example script from the tutorial, such as example1a.tcl,
the following error is shown: 

Error when calling class Oldsim: example1a.tcl

This happens when I have the script in the same directory OR when I have
typed the path which leads to this directory (e.g. % ns
/home/Student/Kenny/ns-allinone-2.27/ns-2.27/example1a.tcl).

I thought that you just had to type ns example1a.tcl at the prompt?

Please help me as this is very urgent,

Thank you in advance,

Kenneth