Error invalid command name “Agent/MyAgentOtcl”

Hi all,
when I run the given tcl file ex-linkage in http://nile.wpi.edu/NS/ I get similar
error msg as follows:

---

invalid command name “Agent/MyAgentOtcl”
while executing
“Agent/MyAgentOtcl create _o3 “
invoked from within
“catch “$className create $o $args” msg”
(procedure “new” line 3)
invoked from within
“new Agent/MyAgentOtcl”
invoked from within
“set myagent [new Agent/MyAgentOtcl]”
(file “ex-linkage.tcl” line 5)
thank you for your response
Mustafa
Regards