[O] ox-pandoc - org-mode + org-ref to docx with bibliographies

[童俊翔]

I’m trying to export org to docx via ox-pandoc, following this guidance,  http://kitchingroup.cheme.cmu.edu/blog/category/docx/

my .emacs is as follows:

(add-to-list 'exec-path "/usr/local/bin")

(require 'ox-pandoc)

(setq helm-bibtex-format-citation-functions

      '((org-mode . (lambda (x) (insert (concat

                                         "\\cite{"

                                         (mapconcat 'identity x ",")

                                         "}")) ""))))

and when I perform C-c C-e p x, the error showed as: 

org-org-link: Symbol's function definition is void: org-export-custom-protocol-maybe

How to solve this problem? Thank you for your help!