Next button doens't work after removing a few items

Is there a setting I need to change when using less or more items with the library? The demo looks great, and we are trying to incorporate to our application. However, the navigation stops working or behaves strangely after we removed items from the list. For example, if we remove four items, the next button stops working after one click. The previous button also shows the wrong picture (wrong index maybe).

Thanks,
Barry