Select Admin--->Wiki and check the slection box "Uses Slideshow". (See below)
Changing Slideshow Appearance
To change the appearance of your slides, select the CSS file to use in the Admin--->General panel. (See below)
Slideshows require a titlebar !!
The 'Slides' link appears on a page when there are 'titlebar' (-=title=-) tags on that page. Titlebar tags are used to indicate new slides for the slideshow.