blocking the posts within the category

for visitors to the site, we don't want them to be able to read posts of certain categories. I have the category blocked and they can't see that. but they can click on the posts within that category and they are able to read them. you can't block posts as it will only show the last 25. it says to block entire category.

I am trying to block Gee-g's pillow talk and what hots.

It was working fine and just stopped working in the last few days. this is my second inquiry about this and need it resolved quickly.

thanks,