I am investigating this, but from a brief search, it looks like an Invasion problem that they plan to correct with a release later this year.
As a work around, searching the forums via Google works well. I searched "Wetpixel classifieds YS-D2":
search_post.jpg 58.23KB 2 downloads
I will keep you posted on whether I can fix the forum search in the interim too.
All the best