When providing extra wrong answers, the graphics in the wrong answers are not displayed. That is, if we leave the question blank, the graphic in the answer will not display. I would expect to see the graphics for all potential answers. Tested on Firefox and Internet Explorer.

To reproduce:
Create a Quiz - add a drag and drop matching question
Add three questions
For the first two, add question text and a graphic for an answer
For the third, add only an answer in the form of a graphic
Save
Preview

The answers without questions are not displayed - they can be dragged and dropped
Have tested with several different graphic fomats from different locations
The properties of the graphics that work
Works
http://wsionline.wsi.tafensw.edu.au/pluginfile.php/101783/qtype_ddmatch/subanswer/67098/1/4624/SIHHHCS302A%20Sect%20Pat.png

Doesn't work
http://wsionline.wsi.tafensw.edu.au/pluginfile.php/101783/qtype_ddmatch/subanswer/67098/1/4627/SIHHHCS303A%20Proj%20Grad%20Sect%20Pat.png