Help on Branching

Hi

I'm trying to create a branching course, but for some reason I can't get the next/previous buttons to display after the final branch to move on in the course.

I've attached an exert from the course. When the timeline on the main slide starts, the next/previous buttons are hidden. The main slide has three hotspots, which move you to three separate branches, they also change the state of three rectangles. When all three rectangles have changed state and the three slides visited the next/previous buttons should then appear. The user should then be able to move to the summary slide and continue the course. I'm clearly missing something, I've tried using state changes and varibles to trigger the next/previous buttons but neither work for me.

Any help would be appreciated

Thanks

Phil