Don't know exactly why the sales are so low on LO. Well, to me they compare to BSP somehow, at least regarding the sales stats. But their community is awesome, the site admins (and the bouncers) are friendlier than anybody, love the design and their uniqueness as well. The uploading system is great too (much, much better than on iStock, for example).
The major reason is probably their age, but there has to be something wrong on the buyer side as well. Marketing primarily and maybe an unlucky search engine. The free images section or something like that would certainly build up it's popularity. They have to come up with an idea to bring in more buyers.
p.s.: I was wondering a couple of days ago how much does offering different content formats (bitmaps and vector, for example) contribute to the popularity of these microstock agencies. And it is certainly one of the top reasons why buyers choose them. The market has diversified and designers are well versed in rasterized AND vector content. And they choose those that offer both (look at SS and iS).
Anyways. I wish all the best to LO, they sure are working hard.