emacs remapping

[Stunning Soldier]

Hi all. Trying to map the following function to C-d

(global-set-key (kbd "C-d") 'my-kill-word)

(defun my-kill-word ()

   (interactive)

   (unless (looking-at "\\<")

     (backward-word))

   (kill-word 1))

When I save this in my .emacs and do "M-x load-file ~/.emacs" it works fine in the .emacs buffer, and in any new buffers I create, but in buffers that I have already worked on/have saved previous to this change, the command doesnt work. It defaults to delete-char. 

I have already tried restarting emacs.