Question on latex source block

[Richard Stanton <stanton@haas.berkeley.edu>]

Using Org-mode version 7.9.1 (release_7.9.1-154-g659be3 @ c:/emacs/site-lisp/org-mode/lisp/), I created the following LaTeX code block:

#+begin_src latex :file test.png
\frac{1}{2}
#+end_src

When I press C-c C-c to compile the code block, I get the following error dump:

Debugger entered--Lisp error: (void-function org-create-formula-image)
  org-create-formula-image("\\frac{1}{2}" "test.png" (:foreground default :background default :scale 1.0 :html-foreground "Black" :html-background "Transparent" :html-scale 1.0 :matchers ("begin" "$1" "$" "$$" "\\(" "\\[")) t)
  org-babel-execute:latex("\\frac{1}{2}" ((:comments . "") (:shebang . "") (:cache . "no") (:padline . "") (:noweb . "no") (:tangle . "no") (:exports . "results") (:results . "file replace latex") (:session . "none") (:hlines . "no") (:padnewline . "yes") (:file . "test.png") (:result-type . value) (:result-params "file" "replace" "latex") (:rowname-names) (:colname-names)))
  org-babel-execute-src-block(nil ("latex" "\\frac{1}{2}" ((:comments . "") (:shebang . "") (:cache . "no") (:padline . "") (:noweb . "no") (:tangle . "no") (:exports . "results") (:results . "file replace latex") (:session . "none") (:hlines . "no") (:padnewline . "yes") (:file . "test.png") (:result-type . value) (:result-params "file" "replace" "latex") (:rowname-names) (:colname-names)) "" nil 0))
  org-babel-execute-src-block-maybe()
  org-babel-execute-maybe()
  org-babel-execute-safely-maybe()
  run-hook-with-args-until-success(org-babel-execute-safely-maybe)
  org-ctrl-c-ctrl-c(nil)
  call-interactively(org-ctrl-c-ctrl-c nil nil)

What am I missing here?

Thanks.

Richard Stanton