Copying to clipboard doesn't work on Emacs Terminal mode

I was faced with the problem which is similar as Mac OS Lion へ Emacs 24.3 をインストール - Shammerism at Emacs 24.3 on Mac OS X Mavericks.
The step is ...

1. Launch terminal
2. emacs -nw
3. Mark
4. move cursor
5. Try to copy by Ctrl-CC

In my environment, Ctrl-CC is defined as original function.

       (defun copy-to-clipboard (p1 p2)
	 (interactive "r*")
	 (ns-set-pasteboard (buffer-substring p1 p2))
	 (message "Copied selection to clipboard"))

But try this command, the following message will be echoed in mini-buffer.

openstep is not in use or not initialized

I have seen this message ever before, that is described in 2013/03/16 my blog. I thought that this is caused by the ns-function-shortage at that time, but this is not correct. Because in my environment, following elisp code returns t, but this message will be output.

(fboundp 'ns-get-pasteboard)
t
(fboundp 'ns-set-pasteboard)
t

I have no idea about the root cause, but using "simpleclip.el" can avoid this issue and this is happened only terminal mode. So I have changed my init file like below.

...
(cond ((and (fboundp 'ns-set-pasteboard)
	    (fboundp 'ns-get-pasteboard)
	    (window-system))
	; cocoa-emacs.
       ;;; Windows mode only...
       (setq interprogram-cut-function nil)
       (setq interprogram-paste-function nil)
       (defun paste-from-clipboard ()
	 (interactive)
	 (and mark-active
	      (filter-buffer-substring (region-beginning) (region-end) t))
	 (insert (ns-get-pasteboard)))
       (defun copy-to-clipboard (p1 p2)
	 (interactive "r*")
	 (ns-set-pasteboard (buffer-substring p1 p2))
	 (message "Copied selection to clipboard"))
       (defun cut-to-clipboard (p1 p2)
	 (interactive "r*")
	 (ns-set-pasteboard (filter-buffer-substring p1 p2 t)))
       (global-set-key "\C-cx" 'cut-to-clipboard);[f5]"\C-cx"
       (global-set-key "\C-cc" 'copy-to-clipboard);[f6]"\C-cc"
       (global-set-key "\C-cv" 'paste-from-clipboard));[f7]"\C-cv")
      (t
       ; The emacs installed by port
       (progn
	 (require 'simpleclip)
	 (simpleclip-mode 1)
	 (global-set-key "\C-cx" 'simpleclip-cut)
	 (global-set-key "\C-cc" 'simpleclip-copy)
	 (global-set-key "\C-cv" 'simpleclip-paste))))
...

This is required "simpleclip.el".