[O] ditaa source gets disappeared by exporting html

[ishi soichi]

emacs 24.3
org-mode 8.2.6

When I run org-html-export-to-html the following code,

#+begin_src ditaa :file ditaa-seqboxes.png+------+   +-----+   +-----+
  +-----+|{io}  |   |{d}  |   |{s}  |   |cBLU || Foo  +---+ Bar +---+
Baz +---+ Moo ||      |   |     |   |     |   |     |+------+
+-----+   +--+--+   +-----+
                        |
           /-----\      |      +------+
           |     |      |      | c1AB |
           | Goo +------+---=--+ Shoo |
           \-----/             |      |
                               +------+#+end_src


it successfully produces an image, which is visible in the exported html.
But the original source of the org file becomes,

#+RESULTS:
[[file:ditaa-seqboxes.png]]

In other words, the source is gone(?).

Is there anyway to maintain the source of the image and export the image in
html?

soichi