The first part of the URL to your images is:
HTML Code:
<div class="attribImg"><img src="thumb.php?src=images/attributes/teaanyoneinvite_jpg.jpg&x=100&y=100&f=0"
suggesting you are using some module add-on to get thumbs and popups.
Without this module, my URL's look like:
HTML Code:
<div class="attribImg"><input type="radio" name="id[12]" value="42" id="attrib-12-42" /><label class="attribsRadioButton three" for="attrib-12-42"><img src="images/attributes/transparent.jpg" alt="" width="50" height="71" /><br />Transparent</label></div>
So the problem is in that thumbs add on...
Try changing the option name TYPE to "Radio Button" rather than "Dropdown" .