[Theme-Natural] How to Use a Slider?

I’m having trouble figuring out how to insert a reflexive slider (using a slideshow) using the shortcode. I have created a slideshow and assigned 5 slides to it. When I insert the shortcode for the slider in the page, no images populate. Instead, a small red X appears in place of the image. Alternatively, the page just cycles and cycles and never displays the slideshow. Any ideas? The documentation doesn’t provide any other details than which shortcodes apply for which sliders.