I downloaded the plugin NextGen Gallery for my WordPress.org, 3.5.1, Twenty Eleven theme. My main purpose is to create a slide show of photos. I know the first step is to select add gallery/images. When I name a gallery and click "Add Gallery" it does not go to the next page of "Add Images", it remains on this page. What is the issue here? Why can't I add images, and then make a slideshow?