Pagination problem

Hello I am having a problem with the pagination not working correctly. I am currently displaying 9 items per page but although the additional images are hidden I cannot access them as the next page link (2) does not appear.

What is strange is if I have a total of 12 images and 9 per page the next page does not appear. If I add 2 more images, so a total of 14, the pagination suddenly works and (2) page two appears and functions correctly.

This seems to be the case for a variation of items per page, such as 6 per page. With a total of 12 items, pagination set to 6 per page, it works fine. If I add 1 or 2 more images, so a total of 14 items, page three (3) does not appear so I cannot view the items. If I add 1 more, so a total of 15, page three (3) appears.

So it seems there is a minimum number of items required for the tabs to work correctly. Can you please help as this is a massive problem for the project I am working on.

Thanks