Your configuration is wrong. You need not to set load-path
manually for
installed packages with package.el. You just call package-initialize
as
below. package-initialize
set load-path
for all installed package
directories.
(package-initialize)
(require 'auto-complete-config)
(add-to-list 'ac-dictionary-directories "~/.emacs.d/elpa/auto-complete-20140414/dict")
(ac-config-default)