The auto-complete-clang-async doesn't work on Emacs as expected

Question

While referring to this webpage, I installed auto-complete-clang-async.el to Emacs. Apparently, auto-completion works when I create a new file.(shown below) But it doesn't work when I saved the file and open it again on emacs. Does anyone know why it happens and how it should be fixed?

Any help would be appreciated. Thanks in advance.

I use Emacs24.3.1 on Ubuntu12.04, which is accessed from Windows 8.1 machine via ssh. clang's version is 3.5. clang-complete binary is build with llvm-config-3.5.

Here is my emacs configuration in .emacs.d/init.el.

(defun add-to-load-path (&rest paths)
  (let (path)
    (dolist (path paths paths)
      (let ((default-directory
              (expand-file-name (concat user-emacs-directory path))))
        (add-to-list 'load-path default-directory)
        (if (fboundp 'normal-top-level-add-subdirs-to-load-path)
            (normal-top-level-add-subdirs-to-load-path))))))

(add-to-load-path "elisp" "conf" "public_repos" "elpa" )

(require 'auto-complete-clang-async)

(defun ac-cc-mode-setup ()
  (setq ac-clang-complete-executable "~/.emacs.d/clang-complete")
  (setq ac-sources '(ac-source-clang-async))
  (ac-clang-launch-completion-process)
)

(defun my-ac-config ()
  (add-hook 'c-mode-common-hook 'ac-cc-mode-setup)
  (add-hook 'auto-complete-mode-hook 'ac-common-setup)
  (global-auto-complete-mode t))

(my-ac-config)

I put the .el file in .emacs.d/elisp directory. There is clang-complete executable in .emacs.d/ directory.

Answer 1

Even though I don't understand why it happens, I've discovered the solution. When auto-completion doesn't work properly, you have to save your current buffer. (Command: C-x C-s) Then the functionality will be effective again.