fatal: did you run git update-server-info on the server? mv post-update.sample post-update

The doc, http://www.kernel.org/pub/software/scm/git/docs/gitcore-tutorial.html, at the the section, "Working with Others" says that
mv post-update.sample post-update under the $GIT_DIR/hooks directory for the public repository. I did that. The file permission is executable.

ls -alF /pub/git/u-boot.git/hooks/post-update
-rwxr-xr-x  1 garyyang6 engr 189 Nov 18 15:54 /pub/git/u-boot.git/hooks/post-update*

But, I got error, "did you run git update-server-info on the server" when I tried to "git pull". Any idea why I got this error?

I did not run post-update at public repository manually. Do I need to run it for the very first time?

At my private repository, I did:
git pull http://git01.my.com /pub/git/u-boot.git HEAD
fatal: http://git01.my.com/info/refs not found: did you run git update-server-info on the server?

Thank you,

Gary