Need help for my slideshow app

I have been working on an app that shows a slideshow pretty much how WhatsApp does. Touching the card changes to the next slide, and the back button goes to the previous one. But unfortunately, the app is sick and shows errors. Anyone there to help?

It would be nice I you could help with the aia file as well.

When back press event triggered, the global index will get reduced by 3. So you will get select list item list index cannot be less than 0

I made a provision because the value x is incremented when I change the progress.

is the progress changed event not triggered when we manually change the progress?

BTW can you tell me the improvement I can make? everything works fine except the backpress event

No such clear inform is in structure

Well, I am moving tto a new method. Thanks for your support.