[ns] make error

[Nikheel Kumar]

hi all

while i am using "make" in my ns directory(ns-2.31):

$ make clean; make depend; make

it gives the following error

Makefile:74: *** missing seperator (did you mean TAB instead of 8 speaces?)
stopped
Makefile:74: *** missing seperator (did you mean TAB instead of 8 speaces?)
stopped
Makefile:74: *** missing seperator (did you mean TAB instead of 8 speaces?)
stopped

i open Makefile.in file and remove above error but still gives the same
problem. please explain what is this error

regards,