emacs: 24.5.1: auto complete not loaded

[Sanjeev Sariya]

Hi,
I'm new to emacs, and setting up emacs.
OS X, version 24.5.1

I've init.el as:
(setq package-archives '(
                         ("melpa" . "http://melpa.org/packages/";)  ("gnu" . 
"http://elpa.gnu.o\
rg/packages/")  )
      )
(require 'package)
(package-initialize)

;;------------------

Ii installed auto-complete from M-x list-packages
searched auto-complete
pressed i
and then pressed x

Package got downloaded, and is present in:

~/.emacs.d/elpa/auto-complete-20160416.604

In my init.el file, I've added:

;;-----
(require 'auto-complete)
(global-auto-complete-mode t) ; autocomplete in all buffers   

;;-----------------------------------------------------

But it doesn't activate auto complete package. 

Kindly help.

Best,
Sanjeev