here is a demostration:

I have "london" images, so a search on my network buddies' sites with the word "london", should return my images, right?

but it doesn't:
http://cartoonpictureshop.com
http://hitvectors.com
you may search with keyword "london" and you will see there are no results, even though there should be..

but when I search for a keyword that my network buddies have my images come up as well:
http://cartoonpictureshop.com/search-images/girl/

http://hitvectors.com/search-images/animal/

when I do it on my site:
http://www.cidepix.com/?image-tags=blue+robot

results from other sites "DO" come up as they should be.. my site does the correct thing by showing results from other sites even though I don't have that keyword.. but other sites don't show mine or any other sites if that keyword is not available on that site.. why is this happening?