Previous and Next button missing on published online help

Webhelp project was published using Robohelp 2015 as responsive html5 using the charcoal grey theme. When previewing the file before generation the Previous and Next buttons/icons were showing for all views (desktop, tablet, and phone). After generating the output though, the buttons are not being displayed.Does anyone have any idea why this is happening, and how to resolve it?

Thanks in advance.