Couple things, when I click on the big pics of the gallery I go here
http://www.sexpicturespass.com/idsignup.cgi?referal=135
Honestly I see nothing on this page that makes me want to pull out my credit card, you are telling them in TEXT ONLY what is on your site. Surfers are horny, they don't want to read a lot of text, they need to be SHOWN what is on your site and why they should pull out their CC, they are not going to read it.
As far as the traffic to that gallery, that is not a popular category at all, I think it is in Brunette babes or something like that. Is this a i-f-r-a-m-e-d order???
Having the first part of the join process on the gallery itself is very smart, I am really surprised you have not had good luck with this gallery, but my gallery rules are designed to get you a high CTR on your gallery, once the surfer is at your paysite, I have no more control, it is up to you to convert him.