[ns] ns installed correctly but couldn't be run, need help!

["Tianyu Zhou(arnie)" <ztianyu@paul.rutgers.edu>]

i just installed ns-2.1b6 allinone on Linux 2.0.36. It telled me install
was successful. But whatever tcl script i run, it just prints pages of
source code like this:
-------------------------------------
	ns:




proc warn {msg} {
global warned_
if {![info exists warned_($msg)]} {
puts stderr "warning: $msg"
set warned_($msg) 1
}
}

if {[info commands debug] == ""} {
proc debug args {
warn {Script debugging disabled.  Reconfigure with --with-tcldebug, and

.
.
.

(finally it says:)

: no value given for parameter "text" to "checkout_executable"
    while executing
"checkout_executable PERL  perl "\
When configured, ns found the right version of perl in\

but it doesn't seem to be there anymore, so\
ns will fall b..."
----------------------------------------------------------

could any one tell me how to fix it? (i'm using perl 5.004_04)
thanks!!!

zhou