How to remove the word "category" from permalink.

I have a book on WordPress that told me how to make a custom structure for my permalinks. I put “/%category%/%postname%/” in the custom structure area. However, when I click on a sub-category from the Menu, it automatically includes the word “category” in the URL. For example, if you click on “Auckland” under the “New Zealand” parent category, it gives you this: http://www.ellevala.com/category/new-zealand/auckland/. When you click it, it says “no results found.” It’s supposed to go to here: http://www.ellevala.com/new-zealand/auckland/day-1/. This post is associated with the Auckland category.

However, if you click the Paihia sub-category, this will go to the right URL (it’s the only one that doesn’t include the word “category” in the URL.

Also, even though I have 3 posts that are assigned the “Paihia” sub-category, it only brings up the one post. Help?!?