It does work because I changed the org-babel code to use `elasticsearch` as a keyword instead. I felt that `es` was a bit too general and didn't explain what was going on. It is fine for the mode to be called `es-mode`, but I thought that the org-babel mode should be more explanatory as we are actually doing literary programming. 

To get it working you need to add the following to your init file:
```elisp
(org-babel-do-load-languages
   'org-babel-load-languages
   '((elasticsearch . t)))
```
You also need to have the path to where `es-mode` is located in your load-path.