Problem with the playreverse button

Hello,

I'm working on a schoolproject, but now i'm stuck. I wanted to create a page flip effect. That worked. But when I click on de 'play reverse' button, the page skips the reverse part.

I've uploaded my project to this link:

Tedx Rens van den Tillaer

When I click on the category design, it all works, but if you go back at the end, the page skips the reverse part. Same for the category 'computers'

The category 'gaming' is working like it is supposed to.

Does anyone know how to fix this?

Cheers,

Rens