[Plugin: Nextgen Gallery] ngg-left/right/center not being assigned to single ima

The site I’m working on is http://www.thelindnerstudio.com
For some of the images in the posts, I’m using the NextGen Gallery (v1.5.5) short code that looks like this:
[singlepic id=3 w=476 h= float=left]
…in order to make the images appear side-by-side.
Problem is, the float=left short code should assign the image a class of “ngg-left” (as float=right should assign “ngg-right” and float=center should be “ngg-center”), but it’s not… at all. Anyone have any ideas? This is the last piece of the puzzle (besides content) and I’d really like to finish this job once and for all.