[ns] How can I create a new object?

["paolo.tegon@libero.it"<paolo.tegon@libero.it>]

Good morning.
If :
-I take the files tbf.cc and tbf.h and everywhere there is "tbf" I 
rewrite "ntbf" and I save these new files in ntbf.cc and ntbf.h, always 
in the directory ../ns-2.1b6
-I modify the file makefile.in adding ntbf.o in the section OBJ_CC
-I add the new default configuration of the parameter (rate_, bucket_, 
qlen_) in ns-default.tcl
-I run ./configure --with-tk --with-tclcl=/root/../tclcl-1.0b9 --with-
otcl=/root/../otcl-1.0a5 (I have problem with only ./configure)
-I run make
-And in a new program I call "set ntbf [new NTBF]" I can read:

invalid command name "NTBF"
	while executing
"NTBF create _o30 "
	invoked from within
"catch "$className create $o $args" msg"
	(procedure "new" line 3)
	invoked from within
"new NTBF"

What can I do?