title: Why Can't I use old theme style file under Emacs 24.1?
body: <p>
  I can use my style file under 23.1, 23.4, but after I update Emacs to 24.1, I can't use the old style files. For example, one of my style files is <a href="https://github.com/credmp/color-theme-arjen/blob/master/color-theme-arjen.el" rel="noreferrer">color-theme-arjen.el</a>. Here is the link:
  </p>
  <p>
  <a href="https://github.com/credmp/color-theme-arjen/blob/master/color-theme-arjen.el" rel="noreferrer">https://github.com/credmp/color-theme-arjen/blob/master/color-theme-arjen.el</a>
  </p>
  <p>
  In my elisp file, I use following code to load the color theme:
  </p>
  (load-file "~/emacs/site-lisp/color-theme/master_color-theme-arjen.el")
  (color-theme-arjen)
  
  <p>
  I don't know why the color theme works under Emacs 23.1 &amp; 23.4 but just doesn't work under Emacs 24.1.
  </p>
  <p>
  While Emacs is loading the file, Emacs gives following error:
  </p>
  Symbol's function definition is void: plist-to-alist
  
  <p>
  If I uncomment above code and don't load the style file, the error is dismissed.
  </p>
  <p>
  Does anyone know why this happens? Or how can I debug it?
  </p>