If you keep building those same galleries that dont make sales.
Then you will not make sales. Please add some text or any reason why someone should sign up.
It's just pictures. Surfers will go "Thats nice" and move on.
I did the same thing also. Then I took the same gallery and added some text on the bottom. I also put images to other sites too. I added text like "With one password you can have access to these other sites too" . Well the gallery converted and now its on sale # 3 at the hun.
Then the next gallery I added some phone sex #'s . Wow some more sales from that same gallery.
Its not rocket science dude. Hope this helps