[ns] make failed in cygwin

[Feng]

Dear ns users,

I'm new to ns2. I am having some problems with make files. 

I added some new .cc codes and needed to rebuild the program. I
performed the following operations

./configure
make depend
make
make install

all the first three operations work well, but when I run the last
command, errors happened,
/usr/bin/install -c -m 555 -o bin -g bin ns usr/local/bin
/usr/bin/install: invalid user 'bin'
make: *** [install-ns] Error 1

can you please tell me what's wrong with it? And what kind of
modifications I should make to the Makefile? I'm using cygwin.

Any help would be greatly appreciated.

Yin